U.S. patent application number 10/971912 was filed with the patent office on 2005-08-04 for battery having electrolyte including organoborate salt.
Invention is credited to Nakahara, Hiroshi, Tsukamoto, Hisashi, Yoon, Sang Young.
Application Number | 20050170253 10/971912 |
Document ID | / |
Family ID | 34812503 |
Filed Date | 2005-08-04 |
United States Patent
Application |
20050170253 |
Kind Code |
A1 |
Yoon, Sang Young ; et
al. |
August 4, 2005 |
Battery having electrolyte including organoborate salt
Abstract
The battery includes an electrolyte activating one or more
cathodes and one or more anodes. The electrolyte includes one or
more mono[bidentate]borate salts in a solvent. The solvent includes
a silane or a siloxane. The mono[bidentate]borate salt can include
a lithium dihalo mono[bidentate]borate such as lithium difluoro
oxalatoborate (LiDfOB).
Inventors: |
Yoon, Sang Young; (Saugus,
CA) ; Nakahara, Hiroshi; (Santa Clarita, CA) ;
Tsukamoto, Hisashi; (Santa Clarita, CA) |
Correspondence
Address: |
MARY ELIZABETH BUSH
QUALLION LLC
P.O. BOX 923127
SYLMAR
CA
91392-3127
US
|
Family ID: |
34812503 |
Appl. No.: |
10/971912 |
Filed: |
October 21, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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60563850 |
Apr 19, 2004 |
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60565211 |
Apr 22, 2004 |
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60606340 |
Sep 1, 2004 |
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60563848 |
Apr 19, 2004 |
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60563849 |
Apr 19, 2004 |
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60563852 |
Apr 19, 2004 |
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60601452 |
Aug 13, 2004 |
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60542017 |
Feb 4, 2004 |
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60543951 |
Feb 11, 2004 |
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60543898 |
Feb 11, 2004 |
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Current U.S.
Class: |
429/307 ;
29/623.1; 429/231.8; 429/313 |
Current CPC
Class: |
H01M 10/0569 20130101;
H01M 4/131 20130101; H01M 10/052 20130101; H01M 4/587 20130101;
Y10T 29/49108 20150115; Y02E 60/10 20130101; H01M 10/0568 20130101;
H01M 10/0567 20130101; H01M 10/0525 20130101; H01M 4/133 20130101;
H01M 4/485 20130101; H01M 50/109 20210101 |
Class at
Publication: |
429/307 ;
429/313; 429/231.8; 029/623.1 |
International
Class: |
H01M 010/40 |
Goverment Interests
[0002] This invention was made with United States Government
support under NIST ATP Award No. 70NANB043022 awarded by the
National Institute of Standards and Technology (NIST). The United
States Government has certain rights in this invention pursuant to
NIST ATP Award No. 70NANB043022 and pursuant to Contract No.
W-31-109-ENG-38 between the United States Government and the
University of Chicago representing Argonne National Laboratory, and
NIST 144 LM01, Subcontract No. AGT DTD 09/09/02.
Claims
We claim:
1. A battery, comprising: an electrolyte activating one or more
anodes and one or more cathodes, the electrolyte including one or
more mono[bidentate]borate salts in a solvent, the solvent
including a silane or a siloxane.
2. The battery of claim 1, wherein the one or more
mono[bidentate]borate salts includes a dihalo
mono[bidentate]borate.
3. The battery of claim 1, wherein the one or more
mono[bidentate]borate salts include a lithium dihalo
mono[bidentate]borate.
4. The battery of claim 1, wherein the one or more
mono[bidentate]borate salts include lithium difluoro oxalatoborate
(LiDfOB).
5. The battery of claim 4, wherein the electrolyte includes a
silane.
6. The battery of claim 4, wherein the electrolyte includes a
disiloxane.
7. The battery of claim 1, wherein at least one of the one or more
anodes includes two components selected from the group consisting
of: carbon beads, carbon fibers, and graphite flakes.
8. The battery of claim 1, wherein at least one of the one or more
anodes includes a carbonaceous mixture that includes carbon beads,
carbon fibers, and graphite flakes.
9. The battery of claim 1, wherein the electrolyte includes one or
more silanes.
10. The battery of claim 9, wherein the electrolyte includes one or
more organic solvents.
11. The battery of claim 9, wherein at least one silane includes a
silicon linked to one or more substituents that each include a
poly(alkylene oxide) moiety or a cyclic carbonate moiety.
12. The battery of claim 9, wherein at least one silane is
represented by SiR.sub.4-x-yR'.sub.xR".sub.y; wherein R is an alkyl
group, an aryl group or a halogen, R'.sub.x is represented by
Formula VIII-A or Formula VIII-C, R".sub.Y is represented by
Formula VIII-B, x is 0 to 4, y is 0 to 4, 4-x-y indicates the
number of R substituents, and x+y is at least 1; Formula VIII-A:
57wherein R.sub.9 is nil or an organic spacer; R.sub.10 is
hydrogen; alkyl or aryl; R.sub.11 is alkyl or aryl; and n is 1 to
15; Formula VIII-B: 58wherein R.sub.12 is an organic spacer and p
is 1 to 2; and Formula VIII-C: 59where R.sub.14 is nil or a spacer;
R.sub.15 is nil or a spacer; R.sub.16 is hydrogen, alkyl or aryl;
second silane represents another silane and n is 1 to 15.
13. The battery of claim 1, wherein the electrolyte includes one or
more disiloxanes.
14. The battery of claim 13, wherein the electrolyte includes one
or more organic solvents.
15. The battery of claim 13, wherein at least one disiloxane
includes a backbone with a silicon linked to one or more
substituents that each include a poly(alkylene oxide) moiety or a
cyclic carbonate moiety.
16. The battery of claim 13, wherein at least one disiloxane is
represented by: 60wherein R.sub.1 is an alkyl group or an aryl
group; R.sub.2 is an alkyl group or an aryl group; R.sub.3 is an
alkyl group or an aryl group; R.sub.4 is an alkyl group or an aryl
group; R.sub.5 is represented by Formula VII-A, Formula VII-B or
Formula VII-C; R.sub.6 is an alkyl group, an aryl group,
represented by Formula VII-D, or represented by Formula VII-E;
Formula VII-A: 61wherein R.sub.9 is nil or a spacer; R.sub.10 is
hydrogen; alkyl or aryl; R.sub.11 is alkyl or aryl; and n is 1 to
12; Formula VII-B: 62wherein R.sub.12 is an organic spacer and p is
1 to 2; Formula VII-C: 63where R.sub.14 is nil or a spacer;
R.sub.15 is nil or a spacer; R.sub.16 is hydrogen, alkyl or aryl;
second siloxane represents another siloxane and n is 1 to 12;
Formula VII-D: 64wherein R.sub.17 is nil or a spacer; R.sub.18 is
hydrogen; alkyl or aryl; R.sub.19 is alkyl or aryl; and q is 1 to
12; and Formula VII-E: 65wherein R.sub.20 is an organic spacer and
p is 1 to 2.
17. The battery of claim 1, wherein the electrolyte includes one or
more trisiloxanes.
18. The battery of claim 17, wherein the electrolyte includes one
or more organic solvents.
19. The battery of claim 17, wherein at least one trisiloxane
includes a backbone with three silicons, one or more of the
silicons being linked to one or more substituents that each include
a poly(alkylene oxide) moiety or a cyclic carbonate moiety.
20. The battery of claim 17, wherein at least one trisiloxane is
represented by: 66wherein R.sub.1 is an alkyl group; R.sub.2 is an
alkyl group; R.sub.3 is an alkyl group or an aryl group; R.sub.4 is
an alkyl group or an aryl group; R.sub.5 is an alkyl group or an
aryl group; R.sub.6 is an alkyl group or an aryl group; R.sub.7 is
represented by Formula V-A or Formula V-B; R.sub.8 is represented
by Formula V-C or Formula V-D; Formula V-A: 67wherein R.sub.9 is
nil or a spacer; R.sub.10 is hydrogen; alkyl or aryl; R.sub.11 is
alkyl or aryl; and n is 1 to 12; Formula V-B: 68wherein R.sub.12 is
an organic spacer and p is 1 to 2; Formula V-C: 69wherein R.sub.13
is nil or a spacer; R.sub.14 is hydrogen; alkyl or aryl; R.sub.15
is alkyl or aryl; and q is 1 to 12; and Formula V-D: 70wherein
R.sub.16 is an organic spacer and p is 1 to 2.
21. The battery of claim 17, wherein at least one trisiloxane is
represented by: 71wherein R.sub.19 is an alkyl group or an aryl
group; R.sub.20 is represented by Formula VI-A, Formula VI-B or
Formula VI-C; Formula VI-A: 72wherein R.sub.21 is an organic spacer
and p is 1 to 2; Formula VI-B: 73wherein R.sub.23 is hydrogen;
alkyl or aryl; R.sub.24 is alkyl or aryl; and r is 1 to 12; and
Formula VI-C: 74where R.sub.25 is nil or a spacer; R.sub.26 is nil
or a spacer; R.sub.27 is hydrogen, alkyl or aryl; second siloxane
represents another siloxane and n is 1 to 12.
22. The battery of claim 1, wherein the electrolyte includes one or
more tetrasiloxanes.
23. The battery of claim 22, wherein at least one tetrasiloxane
includes a backbone with four silicons, one or more of the silicons
being linked to one or more substituents that each include a
poly(alkylene oxide) moiety or a cyclic carbonate moiety.
24. The battery of claim 1, wherein the electrolyte includes one or
more polysiloxanes.
25. The battery of claim 24, wherein at least one polysiloxane
includes a backbone with five or more silicons, one or more of the
silicons being linked to one or more substituents that each include
a poly(alkylene oxide) moiety or a cyclic carbonate moiety.
26. A method of generating a battery, comprising: generating an
electrolyte including one or more mono[bidentate]borate salts in a
solvent, the solvent including a silane or a siloxane; and
activating one or more anodes and one or more cathodes with the
electrolyte.
Description
REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority to U.S. Provisional Patent
Application Ser. No. 60/563,850, filed on Apr. 19, 2004, entitled
"Organoborate Salt in Electrochemical Device Electrolytes;" and to
U.S. Provisional Patent Application Ser. No. 60/565,211, filed on
Apr. 22, 2004, entitled "Organoborate Salt in Electrochemical
Device Electrolytes;" and to U.S. Provisional Patent Application
Ser. No. 60/606,340, filed on Sep. 1, 2004, entitled "Organoborate
Salt in Electrochemical Device Electrolytes;" and to U.S.
Provisional Patent Application Ser. No. 60/563,848, filed on Apr.
19, 2004, entitled "Composition Check for Organoborate Salt
Employed in Electrochemical Device Electrolytes;" and to U.S.
Provisional Patent Application Ser. No. 60/563,849, filed on Apr.
19, 2004, entitled "Battery Employing Electrode Having Graphite
Active Material;" and to U.S. Provisional Patent Application Ser.
No. 60/563,852, filed on Apr. 19, 2004, entitled "Battery Having
Anode Including Lithium Metal;" and to U.S. Provisional Patent
Application Ser. No. 60/601,452, filed on Aug. 13, 2004, entitled
"Electrolyte Including Silane for Use in Electrochemical Devices;"
and to U.S. Provisional Patent Application Ser. No. 60/542,017,
filed on Feb. 4, 2004, and entitled "Nonaqueous Electrolyte
Solvents for Electrochemical Devices;" and to U.S. Provisional
Patent Application Ser. No. 60/543,951, filed on Feb. 11, 2004, and
entitled "Siloxanes;" and to U.S. Provisional Patent Application
Ser. No. 60/543,898, filed on Feb. 11, 2004, and entitled "Siloxane
Based Electrolytes for Use in Electrochemical Devices; and is also
a continuation-in-part of U.S. patent application Ser. No. (Not yet
assigned), filed on Oct. 7, 2004, and entitled "Battery Having
Electrolyte Including One or More Additives;" each of which is
incorporated herein in its entirety.
FIELD
[0003] The present invention relates to electrochemical devices,
and more particularly to electrochemical devices having
electrolytes that include organoborate salts.
BACKGROUND
[0004] The increased demand for lithium batteries has resulted in
research and development to improve the safety and performance of
these batteries. The organic carbonate solvents employed in the
electrolytes of many batteries are associated with high degrees of
volatility, flammability, and chemical reactivity. A variety of
electrolytes that include polysiloxane solvents have been developed
to address these issues.
[0005] Electrolytes having polysiloxane solvents typically have a
low ionic conductivity that limits their use to applications that
do not require high rate performance. Additionally, batteries that
include polysiloxane solvents have shown poor cycling performance
when used in secondary batteries. As a result, lithium bis-oxalato
borate (LiBOB) has been used as the salt in these electrolytes.
However, LiBOB is unstable in the presence of moisture. The amount
of moisture in battery electrolytes and/or electrodes can be on the
order of several hundred ppm. The presence of this moisture can
cause LiBOB to decompose into lithium oxalate (LiHC2O4.H2O) and
form a precipitate in the electrolyte. This precipitate can
increase the internal resistance of electrical devices such as
batteries.
SUMMARY
[0006] A battery is disclosed. The battery includes an electrolyte
activating one or more anodes and one or more cathodes. The
electrolyte includes one or more mono[bidentate]borate salts in a
solvent. The mono[bidentate]borate salt can be a lithium dihalo
mono[bidentate]borate such as lithium difluoro oxalatoborate
(LiDfOB). The solvent includes a silane or a siloxane.
[0007] The siloxanes can include one or more silicons linked to a
substituent that includes a poly(alkylene oxide) moiety or a cyclic
carbonate moiety. The siloxane can be a polysiloxane,
tetrasiloxane, a trisiloxane or a disiloxanes. The silanes can
include a silicon linked to one or more substituents that each
include a poly(alkylene oxide) moiety or a cyclic carbonate
moiety.
[0008] In some instances, the battery has one or more anodes that
include two or three components selected from the group consisting
of: carbon beads, carbon fibers, and graphite flakes. Methods of
forming the battery are also disclosed.
BRIEF DESCRIPTION OF THE FIGURES
[0009] FIG. 1 is a schematic view of a battery.
[0010] FIG. 2 illustrates a cross section of a button cell.
[0011] FIG. 3 compares the cycling performances of a first battery
having an electrolyte with (LiDfOB) salt in a disiloxane with a
second battery having an electrolyte with (LiBOB) salt in the
disiloxane. FIG. 3 also compares the cycling performances of a
battery having LiPF.sub.6 dissolved to 1.0 M in a blend of 2 wt %
VC and 98 wt % of the disiloxanes to the cycling performances of
the second battery.
[0012] FIG. 4 compares the cycling performances of a battery having
an electrolyte with (LiDfOB) salt in a silane with a battery having
an electrolyte with (LiBOB) salt in the silane.
DESCRIPTION
[0013] A battery is disclosed. The battery employs an electrolyte
that includes a salt dissolved in a solvent that includes one or
more siloxanes and/or one or more silanes. In some instances, the
salt can be a mono[bidentate]borate such as lithium dihalo oxalato
borate. An example of a lithium dihalo oxalato borate is lithium
difluoro oxalato borate (LiDfOB). In the presence of moisture,
LiDfOB converts to LiBF.sub.4 and LiBOB and/or other lithium
derivatives. Because moisture in a battery is present at low
concentrations, the resulting LiBOB is also present at low
concentrations. As a result, the precipitation associated with use
of LiBOB salt is reduced when LiDfOB is employed. Accordingly, the
battery can have a reduced internal resistance when compared with
batteries that employ electrolytes with LiBOB.
[0014] The solvent can include or consist of polysiloxanes but
preferably includes or consists of tetrasiloxanes, trisiloxanes
and/or disiloxanes. Tetrasiloxanes, trisiloxanes or disiloxanes can
yield an electrolyte with a lower viscosity than electrolytes that
include similarly structured polysiloxanes. The reduced viscosity
can increase the conductivity of the electrolyte and can improve
wetting of electrodes in an electrochemical device enough to
enhance the homogeneity of the electrolyte distribution in the
cell. Surprisingly, the enhanced homogeneity can be sufficient to
increase the capacity and cycling properties of batteries. For
instance, when the device is repeatedly cycled between 2.7 V and
4.0 V using a charge and discharge rate of 0.2 C after formation of
a passivation layer on the anode, these electrolytes may provide a
secondary battery having a discharge capacity retention greater
than 80% at cycle number 200, and/or a discharge capacity retention
greater than 85% at cycle number 200.
[0015] The solvent can also include or consist of one or more
silanes. Silanes can have a viscosity that is reduced even relative
to similarly structured polysiloxanes, tetrasiloxanes, trisiloxanes
or disiloxanes. The additional reduction in viscosity can further
increase the conductivity of the electrolyte and improve wetting of
electrodes in an electrochemical device enough to further increase
the capacity and cycling properties of batteries. For instance,
when the device is repeatedly cycled between 2.7 V and 4.0 V using
a charge and discharge rate of C/5 after formation of a passivation
layer on the anode, these electrolytes may provide a secondary
battery having a discharge capacity retention greater than 85% at
cycle number 200, a discharge capacity retention greater than 80%
at cycle number 300 or a discharge capacity retention greater than
70% at cycle number 500.
[0016] The tetrasiloxanes, trisiloxanes, disiloxanes and/or silanes
can also provide an electrolyte with high ionic conductivities in
addition to enhanced cycling properties. For instance, one or more
of the silicons in the tetrasiloxanes, trisiloxanes, disiloxanes
and/or silanes can each be linked to a first substituent that
includes a poly(alkylene oxide) moiety. The poly(alkylene oxide)
moieties can help dissolve lithium salts employed in the
electrolyte. Accordingly, the tetrasiloxanes, trisiloxanes,
disiloxanes and/or silanes can provide an electrolyte with a
concentration of free ions suitable for use in batteries.
Additionally, the poly(alkylene oxide) moieties can enhance the
ionic conductivity of the electrolyte at room temperatures. For
instance, these siloxanes and/or silanes can yield an electrolyte
with an ionic conductivity higher than 1.times.10.sup.-4 S/cm at
25.degree. C. or higher than 3.times.10.sup.-4 S/cm at 37.degree.
C. At these performance levels, the electrolytes can be suitable
for use in batteries such as high-energy and long cycle life
lithium secondary batteries, such electrical vehicles, satellite
applications, and biomedical devices such as defibrillators.
[0017] Additionally or alternately, one or more of the silicons in
the tetrasiloxanes, trisiloxanes, disiloxanes and/or silanes can
each be linked to a second substituent that includes a cyclic
carbonate moiety. The cyclic carbonate moieties can have a high
ability to dissolve the salts that are employed in battery
electrolytes. As a result, the carbonates can provide high
concentrations of free ions in the electrolyte and can accordingly
increase the ionic conductivity of the electrolyte. For instance,
these siloxanes and/silanes can yield an electrolyte with an ionic
conductivity higher than 1.times.10.sup.-4 S/cm at 25.degree. C. or
higher than 3.times.10.sup.-4 S/cm at 37.degree. C.
[0018] FIG. 1 is a schematic view of a suitable battery 22. The
battery 22 includes an electrolyte 40 activating a cathode 42 and
an anode 44. A separator 46 separates the cathode 42 and anode 44.
The cathode 42 includes a cathode medium 48 on a cathode substrate
50. The anode 44 includes an anode medium 52 on an anode substrate
54. Although the battery is illustrated as including one anode and
one cathode, the battery can include more than one anode and/or
more than one cathode with the anodes and cathodes each separated
by a separator. Additionally, the battery can have a variety of
different configurations such as stacked configuration, a
"jellyroll" or wound configurations. In some instances, the battery
is hermetically sealed. Hermetic sealing can reduce entry of
impurities into the battery. As a result, hermetic sealing can
reduce active material degradation reactions due to impurities. The
reduction in impurity induced lithium consumption can stabilize
battery capacity.
[0019] Suitable cathode substrates 50 include, but are not limited
to, aluminum, stainless steel, titanium, or nickel substrates. An
example of a cathode substrate that can enhance conductivity is a
carbon coated aluminum current collector. The carbon coating may be
applied using any suitable process known in the art, such as by
coating a paste made of carbon and a binder. The thickness of the
carbon coating can be less than 15 microns, less than 10 microns,
about 3 microns or less, and less than 2 microns.
[0020] The cathode medium 48 includes or consists of one or more
cathode active materials. Suitable cathode active materials
include, but are not limited to, lithium metal oxides, lithium
metal combination oxides, Li.sub.xVO.sub.y, LiCoO.sub.2,
LiNiO.sub.2, LiNi.sub.1-x, Co.sub.yMe.sub.zO.sub.2,
LiMn.sub.0.5Ni.sub.0.5O.sub.2,
LiMn.sub.0.3Co.sub.0.3Ni.sub.0.3O.sub.2, LiFePO.sub.4,
LiMn.sub.2O.sub.4, LiFeO.sub.2, LiMc.sub.0.5Mn.sub.1.5O.sub.4,
LiMn.sub.1.5McO.sub.4, vanadium oxide, carbon fluoride and mixtures
thereof wherein Me is Al, Mg, Ti, B, Ga, Si, Mn, Zn, Mo, Nb, V and
Ag and combinations thereof, and wherein Mc is a divalent metal
such as Ni, Co, Fe, Cr, Cu, and combinations thereof. Example
cathode materials include one or more lithium transition metal
oxides selected from the group consisting of Li.sub.xVO.sub.y,
LiCoO.sub.2, LiNiO.sub.2, LiNi.sub.1-xCo.sub.yMe.sub.zO- .sub.2,
LiMn.sub.0.5Ni.sub.0.5O.sub.2, LiMn.sub.0.3Co.sub.0.3Ni.sub.0.3O.s-
ub.2, LiFePO.sub.4, LiMn.sub.2O.sub.4, LiFeO.sub.2,
LiMc.sub.0.5Mn.sub.1.5O.sub.4.
[0021] The cathode medium 48 can optionally include binders,
conductors and/or diluents such as PVDF, graphite and acetylene
black in addition to the one or more cathode active materials.
Suitable binders include, but are not limited to, PVdF, powdered
fluoropolymer, powdered polytetrafluoroethylene or powdered
polyvinylidene fluoride present at about 1 to about 5 weight
percent of the cathode active material. Suitable conductors and/or
diluents include, but are not limited to, acetylene black, carbon
black and/or graphite or metallic powders such as powdered nickel,
aluminum, titanium and stainless steel.
[0022] A suitable material for the anode substrate 54 includes, but
is not limited to, lithium metal, titanium, a titanium alloy,
stainless steel, nickel, copper, tungsten, tantalum and alloys
thereof.
[0023] The anode medium 52 includes or consists of one or more
anode active materials and a binder. The anode medium 52 includes
or consists of one or more anode active materials and a binder. The
anode active material can include or consist of a metal selected
from Groups IA, IIA and IIIB of the Periodic Table of the Elements.
Examples of these anode active materials include lithium, sodium,
potassium and their alloys and intermetallic compounds. Examples of
suitable alloys include, but are not limited to, Li--Si, Li--Al,
Li--B, Li--Si--B. Another example of a suitable lithium alloy is a
lithium-aluminum alloy. However, increasing the amounts of aluminum
present in the alloy can reduce the energy density of the cell.
Examples of suitable intermetallic compounds include, but are not
limited to, intermetallic compounds that include or consist of two
or more components selected from the group consisting of Li, Ti,
Cu, Sb, Mn, Al, Si, Pb, Sn, In, Bi, Ag, Ba, Ca, Hg, Pd, Pt, Te, Zn
and La. Example of intermetallic compounds include
Cu.sub.6Sn.sub.5, Cu.sub.2Sb, MnSb. Other suitable anode active
materials include lithium titanium oxides such as
Li4Ti.sub.5O.sub.12, silica alloys and mixtures of the above anode
active materials.
[0024] Another example of a suitable anode active material includes
or consists of a carbonaceous mixture. For instance, the
carbonaceous mixture can include a mixture that includes or
consists of one, two or three components selected from the group
consisting of: carbon beads, carbon fibers, and graphite
flakes.
[0025] The carbon beads can have shapes that approximate blocks,
spheres, sphereoids, cylinders, cubes or combinations of these
shapes. In some instances, the carbon beads have a real density of
greater than 2.2 g/cc; a surface area of less than 3 m.sup.2/g or
less than 2 m.sup.2/g, or less than 1 m.sup.2/g as measured by BET
where BET is the analytical method employed to measure the specific
surface area of powder based on the BET adsorption isotherm
reported by Brunauer, Emmert, and Teller; and/or an average
particle size of less than 40 .mu.m and/or in a range of 5-35
.mu.m. In some instances, the carbon beads may have a structure
that is inherently rigid. Alternatively or additionally, the carbon
beads may have a rigid surface layer that makes them difficult to
deform. For instance, the carbon beads can have a rigid surface
layer that includes hard carbon. The carbon beads can provide
structural support to the anode medium 52 of the present invention.
The structural support can help maintain the porosity of the anode
medium 52. The porosity of the anode medium 52 can enhance the
contact between the electrolyte and the carbon. Additionally, the
bead shape can help minimize the surface area of the graphite
within the carbonaceous mixture. As a result, the carbon beads can
limit the amount of lithium required to form a passivation layer,
or solid electrolyte interface (SEI) on the anode. Carbon beads
generally have fewer side reactions such as electrolyte
decomposition relative to other shapes of carbon materials. The
carbon beads may be mesocarbon microbeads produced by subjecting
mesophase spherules, produced during the carbonization of pitch, to
heat treatment for graphitization. An example of the carbon beads
is mesocarbon microbeads (MCMB) which are available from Osaka Gas
Chemicals Co., LTD.
[0026] In some instances, the carbon fibers have a specific surface
area of less than 5 m.sup.2/g; an average particle size of less
than 40 .mu.m and/or in a range of 5-35 .mu.m; a d002 (layer
distance) of less than 3.36 .ANG.; and an Lc of greater than 100
nm. Carbon fibers that are too long may cause microshorts by
penetrating the separator 46. The carbon fibers can improve packing
density and conductivity. Carbon fibers can also intensify the
stiffness of the anode and reduce swelling and decomposition of the
anode. The carbon fibers may be a vapor grown carbon fiber. The
carbon fiber may be prepared by subjecting hydrocarbons such as
benzene, methane, propane, and so on to vapor phase
heat-decomposition under the presence of catalyst base plate made
of Fe, Ni, Co, and so on in order to make carbon fibers deposit and
grow on the base plate. Other examples are pitch carbon fibers,
made from petroleum or coal pitch as a raw material through a
spinning and carbonating treatment, and carbon fibers made from
polyacrylonitrile (PAN), which may be used in the invention.
[0027] The graphite flakes can be natural or artificial graphite
flakes. The graphite flakes can be softer than carbon beads. The
flakes tend to reduce friction in the carbon mixture because the
planes of carbon can slip with respect to one another, allowing the
graphite flakes to fit within the spaces in the mixture. In some
instances, the graphite flakes are less than 40 .mu.m or in a range
5-35 .mu.m.
[0028] When the anode active material includes carbon beads, the
carbon fibers, and the graphite flakes, the anode medium 52 can
have a porosity of 25-45%, and the cathode medium 48 can have a
porosity of 20-40%.
[0029] An example embodiment of the anode active material includes
or consists of carbon beads and carbon fibers. A further example
embodiment of the anode active material includes carbon beads and
carbon fibers and excludes carbon flakes. Another example
embodiment of the anode active material includes or consists of
carbon beads, carbon fibers, and graphite flakes. In another
example, the anode active material includes carbon beads, carbon
fibers, and graphite flakes with an average particle size of less
than 40 .mu.m, in a ratio of approximately 70% carbon beads: 22.5%
carbon fibers: 7.5% graphite flakes. Additional description of
anodes constructed with a carbonaceous mixture are provided in U.S.
patent application Ser. No. 10/264,870, filed on Oct. 3, 2002,
entitled "Negative Electrode for a Nonaqueous Battery," and
incorporated herein in its entirety, which claims priority to U.S.
Provisional Patent Application Ser. No. 60/406,846, filed on Aug.
29, 2002, and entitled "Negative Electrode for a Nonaqueous
Battery," and incorporated herein in its entirety.
[0030] Suitable binders for use with the anode medium include, but
are not limited to, PVdF. When the anode active material includes a
carbonaceous mixture, the binder of the anode medium can exclude
fluorine, and can include carboxymethyl cellulose (CMC). Styrene
butadiene rubber (SBR) can be added to impart elasticity to the
mixture. As an alternative to a binder that consists of CMC and
SBR, a different fluorine excluding binder or a fluorine-containing
binder may be used. A dispersion in water of the carbonaceous
mixture, CMC, and SBR can be made to form a slurry that can be
coated onto to a metal foil substrate.
[0031] In some instances, the anode consists of the anode medium.
Accordingly, the anode medium also serves as the anode substrate.
For instance, the anode can consist of lithium metal.
[0032] Suitable separators 46 include, but are not limited to,
polyolefins such as polyethylene. Illustrative separator materials
also include fabrics woven from fluoropolymeric fibers including
polyvinylidine fluoride, polyethylenetetrafluoroethylene, and
polyethylenechlorotrifluor- oethylene used either alone or
laminated with a fluoropolymeric microporous film, non-woven glass,
polypropylene, polyethylene, glass fiber materials, ceramics,
polytetrafluoroethylene membrane commercially available under the
designation ZITEX (Chemplast Inc.), polypropylene/polyethylene
membrane commercially available under the designation CELGARD
(Celanese Plastic Company, Inc.), a membrane commercially available
under the designation DEXIGLAS (C. H. Dexter, Div., Dexter Corp.),
and a polyethylene membrane commercially available from Tonen
Chemical Corp.
[0033] The electrolyte can include one or more salts in a solvent.
The one or more salts can include or consist of an organoborate
salts. Suitable organoborate salts for use with the battery include
mono[bidentate]borates. For instance, the salt can be a dihalo
mono[bidentate]borate such as a dihalo oxalato borate. An example
of a dihalo oxalato borate is a difluoro oxalato borate. The
organoborate salts can be lithium organoborate salts such as
lithium mono[bidentate]borate. For instance, the salt can be a
lithium dihalo mono[bidentate]borate such as a lithium dihalo
oxalato borate. A preferred lithium dihalo oxalato borate is a
lithium difluoro oxalato borate (LiDfOB).
[0034] The organoborate salt can include a boron linked directly to
two halogens and also linked directly to two oxygens that are
linked to one another by an organic moiety. The organic moiety
and/or the second organic moiety can be: substituted or
unsubstituted; and/or branched or unbranched; and/or saturated or
unsaturated. The backbone of the organic moiety can include only
carbons or can include carbons and one or more oxygens. In some
instances, the organic moiety is completely or partially
halogonated. In one example, the organic moiety is fluorinated.
[0035] An example of the organoborate salt is represented by the
following Formula I: 1
[0036] wherein M.sup.+ is a metal ion selected from the Group I or
Group II elements; Y.sub.3 is selected from the group consisting of
--CX(CR.sub.2).sub.aCX--, --CZZ'(CR.sub.2).sub.aCZZ'--,
--CX(CR.sub.2).sub.aCZZ'--, --SO.sub.2(CR.sub.2).sub.bSO.sub.2--,
and --CO(CR.sub.2).sub.bSO.sub.2--; X is .dbd.O or .dbd.NR', Z is
alkyl, halogenated alkyl, --C.dbd.NR', CR'.sub.3 or R'; Z' is
alkyl, halogenated alkyl, --C.dbd.NR', CR'.sub.3 or R'; R" is a
halogen; R' is halogen or hydrogen; R is hydrogen, alkyl,
halogenated alkyl, cyano, or halogen; a is 0 to 4 and b is 1 to 4.
M.sup.+ is preferably selected from Group I and is most preferably
lithium. Z and Z' can be the same or different. The R" can be the
same or different. The R' can be the same or different. The R can
be the same or different.
[0037] In an example of an organoborate salt according to Formula
II, Y.sub.3 is --CX(CR.sub.2).sub.aCX--; each X is .dbd.O and each
R" is a halogen. In another example of the organoborate salt,
Y.sub.3 is --CX(CR.sub.2).sub.aCX-- and each R" is a fluorine.
[0038] The electrolyte can include one or more salts in addition to
the organoborate salt. Suitable salts for use with the electrolyte
include, but are not limited to, alkali metal salts including
lithium salts. Examples of lithium salts include LiClO.sub.4,
LiBF.sub.4, LiAsF.sub.6, LiPF.sub.6, LiSbF.sub.6,
LiCF.sub.3SO.sub.3, LiC.sub.6F.sub.5SO.sub.3,
LiC(CF.sub.3SO.sub.2).sub.3, LiN(SO.sub.2C.sub.2F.sub.5).sub.2,
LiN(SO.sub.2CF.sub.3).sub.2, LiAlCl.sub.4, LiGaCl.sub.4, LiSCN,
LiO.sub.2, LiO.sub.3SCF.sub.3, LiO.sub.2CCF.sub.3, LiSO.sub.6F,
LiB(C.sub.6H.sub.5).sub.4, Li-methide, Li-imide, lithium alkyl
fluorophosphates and mixtures thereof. Additionally or alternately,
the one or more salts can include organoborate salts in addition to
the monobidentate borates disclosed above. For instance, the one or
more salts can include a bis-bidentate borate such as lithium
bis-oxalato borate (LiBOB). Examples of other organoborate salts
are disclosed in U.S. Provisional Patent Application Ser. No.
60/565,211, filed on Apr. 22, 2004, entitled "Organoborate Salt in
Electrochemical Device Electrolytes," and incorporated herein in
its entirety; and in U.S. Provisional Patent Application Ser. No.
60/563,850, filed on Apr. 19, 2004, entitled "Organoborate Salt in
Electrochemical Device Electrolytes," and incorporated herein in
its entirety; and in U.S. Provisional Patent Application Ser. No.
60/563,848, filed on Apr. 19, 2004, entitled "Composition Check for
Organoborate Salt Employed in Electrochemical Device Electrolytes,"
and incorporated herein in its entirety.
[0039] The electrolyte can be prepared such that the concentration
of the one or more salts in the electrolytes is about 0.3 to 2.0 M,
about 0.5 to 1.5 M, or about 0.7 to 1.2 M. The one or more
mono[bidentate]borate salts are preferably present in the
electrolyte at a concentration of about 0.3 to 2.0 M, about 0.5 to
1.5 M, or about 0.7 to 1.2 M. In some instances, the one or more
mono[bidentate]borate salts are present in a concentration less
than 0.3 M or less than 0.1 M and other salts are present in the
electrolyte.
[0040] The solvent can include or consist of one or more
polysiloxanes having a backbone with five or more silicons. One or
more of the silicons can be linked to a first substituent and/or to
a second substituent. The first substituent includes a
poly(alkylene oxide) moiety and the second substituent includes a
cyclic carbonate moiety. Suitable first substituents include side
chains or cross links to other polysiloxanes. Further, each of the
first substituents can be the same or different. In one example of
the polysiloxane, each of the first substituents is a side chain.
Suitable second substituents include side chains. Further, each of
the second substituents can be the same or different. Each of the
second substituents can be the same or different. In some
instances, the terminal silicons in the backbone are not linked to
either a first substituent or a second substituent. Each of the
non-terminal silicons can be linked to at least one first
substituent or to at least one second substituent. In some
instances, the polysiloxane excludes second substituents. One or
more of the silicons in the backbone of the polysiloxane can be
linked to a cross-link to another polysiloxane. The cross-link can
include a poly(alkylene oxide) moiety. Examples of suitable
polysiloxanes are disclosed in U.S. patent application Ser. No.
10/810,019, filed on Mar. 25, 2004, entitled "Polysiloxane for Use
in Electrochemical Cells," and incorporated herein in its
entirety.
[0041] Examples of suitable polysiloxanes have a structure
according to General Formula II: 2
[0042] where R is alkyl or aryl; R.sub.1 is alkyl or aryl; R.sub.3
is represented by: 3
[0043] R.sub.4; is a cross link that links the polysiloxane
backbone to another polysiloxane backbone; R.sub.5 is represented
by: 4
[0044] R.sub.6 is represented by: 5
[0045] R.sub.7 is hydrogen; alkyl or aryl; R.sub.8 is alkyl or
aryl; R.sub.9 is oxygen or an organic spacer; R.sub.10 is an oxygen
or an organic spacer; k is 0 or greater than 0; p is 3, greater
than 3 and/or less than 20; q is 1 to 2; m is 0 or greater than 0
and n is 0 or greater than 0 and can be 2 to 25. In some instances,
n+m+k is 3 or greater than 3. In some instances, m is greater than
0 and a ratio of n:m is 1:1 to 100:1 and is more preferably 5:1 to
100:1. One or more of the alkyl and/or aryl groups can be
substituted, unsubstituted, halogenated, and/or fluorinated. A
suitable organic spacer can include one or more --CH.sub.2--
groups. Other suitable spacers can include an alkylene, alkylene
oxide, or bivalent ether moiety. These spacers can be substituted
or unsubstituted. The above spacers can be completely or partially
halogenated. For instance, the above spacers can be completely or
partially fluorinated. In one example, R.sub.9 is represented by:
--O--(CH.sub.2).sub.3--O-- or --(CH.sub.2).sub.3--O-- with the
oxygen linked to the polyethylene oxide moiety. In another example,
R.sub.10 is represented by: --CH.sub.2--O--(CH.sub.2).sub.3-- where
the single --CH.sub.2-- group is positioned between the carbonate
and the oxygen or --CH.sub.2--O--.
[0046] In instances, where a polysiloxane according to Formula II
includes one or more cross links, a suitable ratio for (number of
cross links): (m+n) includes, but is not limited to, a ratio in a
range of 1:4 to 1:200, in a range of 1:6 to 1:100, or in a range of
1:6 to 1:70.
[0047] Each of the R.sub.3 can be the same or different. In some
instances, one of the R.sub.3 includes a poly(alkylene oxide)
moiety and another R.sub.3 includes a cyclic carbonate moiety. The
structures of R.sub.3 can be the same as the structure of R.sub.5.
In some instances, the R.sub.3 structures are different from the
R.sub.5 structures. When m is greater than 0, the structures of
R.sub.3 can be the same as the structure of R.sub.6. In some
instances, the R.sub.3 structures are different from the structure
of R.sub.6. In some instances, m is 0 and R.sub.3 and R.sub.5 each
have a structure according to: 6
[0048] and the structures for R.sub.3 are different from the
structure for R.sub.5 or the same as the structure for R.sub.5.
[0049] When a polysiloxane according to General Formula I is to be
employed in an electrolyte, a suitable average molecular weight for
the polysiloxane includes, but is not limited to, an average
molecular weight less than or equal to 3000 g/mole.
[0050] The solvent can include or consist of one or more
tetrasiloxanes. Tetrasiloxanes can have a reduced viscosity
relative to similarly structured tetrasiloxanes. A suitable
tetrasiloxane has a backbone with two central silicons and two
terminal silicons. One or more of the silicons can be linked to a
first substituent and/or to a second substituent. The fist
substituent includes a poly(alkylene oxide) moiety and the second
substituent includes a cyclic carbonate moiety. Suitable first
substituents include side chains or cross links to other
tetrasiloxanes. Further, each of the first substituents can be the
same or different. In one example of the tetrasiloxane, each of the
first substituents is a side chain. Suitable second substituents
include side chains. Further, each of the second substituents can
be the same or different. Each of the second substituents can be
the same or different. In some instances, the terminal silicons in
the backbone are not linked to either a first substituent or a
second substituent. Each of the central silicons can be linked to
at least one first substituent or to at least one second
substituent. In some instances, the tetrasiloxane excludes second
substituents. One or more of the silicons in the backbone of the
tetrasiloxane can be linked to a cross-link to another
tetrasiloxane. The cross-link can include a poly(alkylene oxide)
moiety. Examples of suitable tetrasiloxanes are disclosed in U.S.
Provisional Patent Application Ser. No. 60/543,951, filed on Feb.
11, 2004, entitled "Siloxanes," and incorporated herein in its
entirety.
[0051] An example of a suitable tetrasiloxane includes a backbone
with a first silicon linked to a first side chain that includes a
poly(alkylene oxide) moiety. Additionally, a second silicon in the
backbone is linked to a second side chain that includes a
poly(alkylene oxide) moiety or a cyclic carbonate moiety. In some
instances, the first silicon and the second silicon are each
terminal silicons. In other instances, the first silicon and the
second silicon are each central silicons.
[0052] As the number of substituents that include a poly(alkylene
oxide) moiety and/or a cyclic carbonate moiety increases, the
viscosity of an electrolyte can increase undesirably and/or the
ionic conductivity of an electrolyte can decrease undesirably. As a
result, in some instances, the tetrasiloxane includes no more than
two poly(alkylene oxide) moieties or no more than one poly(alkylene
oxide) moiety. Additionally or alternately, the tetrasiloxane can
include no more than two carbonate moieties or no more than one
carbonate moiety. For instance, a third one of the silicons and a
fourth one of the silicons can each be linked to entities that each
exclude a poly(alkylene oxide) moiety and/or that each exclude a
cyclic carbonate moiety. For instance, the third silicon and the
fourth silicon can each be linked to substituents such as side
chains that each exclude a poly(alkylene oxide) moiety and/or that
each exclude a cyclic carbonate moiety. In some instances, the
entities linked to the backbone of the tetrasiloxane other than the
first side chain and the second side chain each exclude a
poly(alkylene oxide) moiety and/or a cyclic carbonate moiety. For
instance, the entities linked to the backbone of the tetrasiloxane
other than the first side chain and the second side chain can each
be a substituent such as a side chain and each of these
substituents can exclude a poly(alkylene oxide) moiety and/or a
cyclic carbonate moiety.
[0053] A silicon on the tetrasiloxane backbone can be linked
directly to a poly(alkylene oxide) moiety or a spacer can be
positioned between the poly(alkylene oxide) moiety and the silicon.
The spacer can be an organic spacer. When the first silicon and the
second silicon are each central silicons linked directly to a side
chain that includes a poly(alkylene oxide) moiety, the
poly(alkylene oxide) moieties each include an oxygen linked
directly to the backbone. The poly(alkylene oxide) moiety can be an
oligo(alkylene oxide) moiety. In some instances, the poly(alkylene
oxide) moiety is a poly(ethylene oxide) moiety.
[0054] When a silicon is linked to side chains that includes a
cyclic carbonate moiety, the side chain can include a spacer that
links the carbonate moiety to the silicon or an oxygen can link the
cyclic carbonate moiety to the silicon. The spacer can be an
organic spacer.
[0055] In instances where the first silicon and the second silicons
are each terminal silicons, the first and second silicons can each
be linked to a side chain that includes a poly(alkylene oxide)
moiety. Formula III provides an example of a tetrasiloxane where
the first silicon and the second silicon are each terminal silicons
linked to a side chain that includes a polyethylene oxide moiety.
Formula III: 7
[0056] wherein R.sub.1 is an alkyl group; R.sub.2 is an alkyl
group; R.sub.3 is an alkyl group or an aryl group; R.sub.4 is an
alkyl group or an aryl group; R.sub.5 is an alkyl group or an aryl
group; R.sub.6 is an alkyl group or an aryl group; R.sub.7 is nil
or a spacer; R.sub.8 is nil or a spacer; R.sub.9 is a hydrogen, an
alkyl group or an aryl group; R.sub.10 is a hydrogen, an alkyl
group or an aryl group; R.sub.11 is an alkyl group or an aryl
group; and R.sub.12 is an alkyl group or an aryl group; x is 1 or
greater and/or 12 or less and y is 1 or greater and/or 12 or less.
One or more of the alkyl and/or aryl groups can be substituted,
unsubstituted, halogenated, and/or fluorinated. The spacers can be
organic spacers and can include one or more --CH.sub.2-- groups.
Other suitable spacers can include an alkylene, alkylene oxide or a
bivalent ether group. These spacers can be substituted or
unsubstituted. The above spacers can be completely or partially
halogenated. For instance, the above spacers can be completely or
partially fluorinated. In one example, R.sub.7 and R.sub.8 are each
nil or are each a spacer. In one example, R.sub.7 and/or R.sub.8 is
represented by: --(CH.sub.2).sub.3--. In one example: R.sub.1;
R.sub.2; R.sub.3; R.sub.4; R.sub.5; R.sub.6; R.sub.11; and R.sub.12
are each methyl groups.
[0057] Examples of preferred tetrasiloxanes according to Formula
III are represented by Formula III-A through Formula III-B. Formula
Ill-A illustrates an example of a tetrasiloxane having terminal
silicons linked to side chains that include an organic spacer
linking a poly(alkylene oxide) moiety to a terminal silicon.
Formula Ill-B illustrates an example of a tetrasiloxane having
terminal silicons that are each linked to an oxygen included in a
poly(alkylene oxide) moiety.
[0058] Formula III-A: 8
[0059] wherein n is 1 to 12 and m is 1 to 12.
[0060] Formula III-B: 9
[0061] wherein n is 1 to 12 and m is 1 to 12.
[0062] Another suitable tetrasiloxane has a backbone with one of
two central silicons linked to a side chain that includes a
poly(alkylene oxide) moiety and the other central silicon linked to
a side chain that includes a poly(alkylene oxide) moiety or a
carbonate moiety. When each of the central silicons is linked to a
side chain that includes a poly(alkylene oxide) moiety, the
poly(alkylene oxide) moieties each include an oxygen linked
directly to a silicon in the backbone.
[0063] Another example of a suitable tetrasiloxane is represented
by Formula IV.
[0064] Formula IV: 10
[0065] wherein: R.sub.20 is an alkyl group or an aryl group;
R.sub.21 is an alkyl group or an aryl group; R.sub.22 is
represented by Formula IV-A; R.sub.23 is represented by Formula
IV-B or IV-C and each Z is an alkyl or an aryl group. The Zs can be
the same or can be different.
[0066] Formula IV-A: 11
[0067] wherein R.sub.24 is an organic spacer or nil; R.sub.25 is
hydrogen, alkyl or aryl; R.sub.26 is alkyl or aryl and p is 1 or
more and/or 12 or less. The organic spacer and can include one or
more --CH.sub.2-- groups. Other suitable spacers can include an
alkylene, alkylene oxide or a bivalent ether group. These spacers
can be substituted or unsubstituted. The above spacers can be
completely or partially halogenated. For instance, the above
spacers can be completely or partially fluorinated. In one example,
R.sub.24 is represented by: --(CH.sub.2).sub.3--.
[0068] Formula IV-B: 12
[0069] wherein R.sub.28 is hydrogen, alkyl or aryl; R.sub.29 is
alkyl or aryl; q is 1 or more and/or 12 or less.
[0070] Formula IV-C: 13
[0071] wherein R.sub.30 is an organic spacer and r is 1 or 2.
Suitable organic spacers for Formula IV through IV-C can include
one or more --CH.sub.2-- groups. Other suitable spacers can include
an alkylene, alkylene oxide or a bivalent ether group. These
spacers can be substituted or unsubstituted. The above spacers can
be completely or partially halogenated. For instance, the above
spacers can be completely or partially fluorinated. In one example,
R.sub.30 is a bivalent ether moiety represented by:
--CH.sub.2--O--(CH.sub.2).sub.3-- with the --(CH.sub.2).sub.3--
linked to a silicon on the backbone of the tetrasiloxane. In
another example, R.sub.30 is an alkylene oxide moiety represented
by: --CH.sub.2--O-- with the oxygen linked to a silicon on the
backbone of the tetrasiloxane.
[0072] One or more of the alkyl and aryl groups specified in
Formula IV through Formula IV-C can be substituted, unsubstituted,
halogenated, and/or fluorinated. When R.sub.23 is according to
Formula IV-B, R.sub.24 can be nil or can be a spacer. In one
example, R.sub.23 is according to Formula IV-C and R.sub.30 is
represented by: --CH.sub.2--O--(CH.sub.2).su- b.3-- where the
single --CH.sub.2-- group is positioned between the carbonate and
the oxygen. In an example, the Zs, R.sub.20, R.sub.21, R.sub.26,
and R.sub.29 are each a methyl group. In another example, R.sub.22
is represented by Formula IV-A and R.sub.23 is represented by
Formula IV-B and in another example R.sub.23 is represented by
Formula IV-A and R.sub.23 is represented by Formula IV-C.
[0073] Examples of tetrasiloxanes according to Formula IV are
represented by Formula IV-D through Formula IV-F. Formula IV-D
represents a tetrasiloxane where each of the central silicons is
linked to a side chain that includes a poly(ethylene oxide) moiety.
The central silicons are each linked directly to an oxygen included
in a poly(ethylene oxide) moiety. Formula IV-E and Formula IV-F
each represent an example of a tetrasiloxane wherein a central
silicon is linked to a side chain that includes a poly(alkylene
oxide) moiety and another central silicon is linked to a side chain
that includes a carbonate moiety. In Formula IV-E, an organic
spacer is positioned between the poly(alkylene oxide) moiety and
the silicon. In Formula IV-F, a silicon is linked directly to an
oxygen included in a poly(alkylene oxide) moiety.
[0074] Formula IV-D: 14
[0075] wherein n is 1 to 12.
[0076] Formula IV-E: 15
[0077] wherein n is 1 to 12.
[0078] Formula IV-F: 16
[0079] wherein n is 1 to 12.
[0080] The solvent can include or consist of one or more
trisiloxanes. Trisiloxanes can have a reduced viscosity relative to
similarly structured, polysiloxanes and tetrasiloxanes. A suitable
trisiloxane has a backbone with three silicons. One or more of the
silicons is linked to a first substituent and/or to a second
substituent. The fist substituent includes a poly(alkylene oxide)
moiety and the second substituent includes a cyclic carbonate
moiety. Suitable first substituents include side chains or cross
links to other trisiloxanes. When the trisiloxanes includes more
than one first substituent, each of the first substituents can be
the same or different. In one example of the polysiloxane, each of
the first substituents is a side chain. Suitable second
substituents include side chains. When the trisiloxanes includes
more than one second substituent, each of the second substituents
can be the same or different. In some instances, the terminal
silicons in the backbone are not linked to either a first
substituent or a second substituent. The central silicons can be
linked to at least one first substituent or to at least one second
substituent. In some instances, the trisiloxane excludes second
substituents. One or more of the silicons in the backbone of the
trisiloxane can be linked to a cross-link to another trisiloxane.
The cross-link can include a poly(alkylene oxide) moiety. Examples
of suitable trisiloxanes are disclosed in U.S. Provisional Patent
Application Ser. No. 60/543,951, filed on Feb. 11, 2004, entitled
"Siloxane," and incorporated herein in its entirety; and U.S.
Provisional Patent Application Ser. No. 60/542,017, filed on Feb.
4, 2004, entitled "Nonaqueous Electrolyte Solvents for
Electrochemical Devices," and incorporated herein in its entirety;
and U.S. Provisional Patent Application Ser. No. 60/543,898, filed
on Feb. 11, 2004, entitled "Siloxane Based Electrolytes for Use in
Electrochemical Devices," and incorporated herein in its
entirety.
[0081] A suitable trisiloxane includes a backbone with a first
terminal silicon, a central silicon and a second terminal silicon.
The first terminal silicons is linked to a first side chain that
includes a poly(alkylene oxide) moiety or that includes a cyclic
carbonate moiety. The second terminal silicon is linked to a second
side chain that includes a poly(alkylene oxide) moiety or that
includes a cyclic carbonate moiety. The first side chain and the
second side chain can each include a poly(alkylene oxide) moiety or
can each include a cyclic carbonate moiety. Alternately, the first
side can include a poly(alkylene oxide) moiety and the second side
chain can include a cyclic carbonate moiety. In one example, the
second side chain includes a cyclic carbonate moiety and the first
side chain includes an organic spacer linking a poly(alkylene
oxide) moiety to the first terminal silicon.
[0082] As the number of substituents that include a poly(alkylene
oxide) moiety and/or a cyclic carbonate moiety increase, the
viscosity of an electrolyte can increase undesirably and/or the
ionic conductivity of an electrolyte can decrease undesirably. As a
result, the trisiloxane can include no more than two poly(alkylene
oxide) moieties or no more than one poly(alkylene oxide) moiety.
Additionally or alternately, the trisiloxane can include no more
than two carbonate moieties or no more than one carbonate moiety.
For instance, each of the entities linked to the central silicon
can exclude a poly(alkylene oxide) moiety and/or a cyclic carbonate
moiety. Additionally or alternately, the entities linked to the
first terminal silicon other than the first side chain and the
entities linked to the second terminal silicon other than the
second side chain can each exclude a poly(alkylene oxide) moiety
and/or a cyclic carbonate moiety. In one example, each of the
entities linked to the silicons in the backbone of the trisiloxane
other than the first side chain and other than the second side
chain exclude both a poly(alkylene oxide) moiety and a cyclic
carbonate moiety. Examples of entities that may be linked to the
silicons include, but are not limited to, substituents such as side
chains, cross-links and halogens.
[0083] Formula V provides an example of the trisiloxane. Formula V:
17
[0084] wherein R.sub.1 is an alkyl group; R.sub.2 is an alkyl
group; R.sub.3 is an alkyl group or an aryl group; R.sub.4 is an
alkyl group or an aryl group; R.sub.5 is an alkyl group or an aryl
group; R.sub.6 is an alkyl group or an aryl group; R.sub.7 is
represented by Formula V-A or Formula V-B; R.sub.8 is represented
by Formula V-C or Formula V-D.
[0085] Formula V-A: 18
[0086] wherein R.sub.9 is nil or a spacer; R.sub.10 is hydrogen;
alkyl or aryl; R.sub.11 is alkyl or aryl; and n is 1 to 12. The
spacer can be an organic spacer and can include one or more
--CH.sub.2-- groups. Other suitable spacers can include an
alkylene, alkylene oxide or a bivalent ether group. These spacers
can be substituted or unsubstituted. The above spacers can be
completely or partially halogenated. For instance, the above
spacers can be completely or partially fluorinated. In one example,
R.sub.9 is represented by: --(CH.sub.2).sub.3--.
[0087] Formula V-B: 19
[0088] wherein R.sub.12 is an organic spacer and p is 1 to 2. The
spacer can be an organic spacer and can include one or more
--CH.sub.2-- groups. Other suitable spacers can include an
alkylene, alkylene oxide or a bivalent ether group. These spacers
can be substituted or unsubstituted. The above spacers can be
completely or partially halogenated. For instance, the above
spacers can be completely or partially fluorinated. In one example,
R.sub.12 is a bivalent ether moiety represented by:
--CH.sub.2--O--(CH.sub.2).sub.3-- with the --(CH.sub.2).sub.3--
linked to a silicon on the backbone of the trisiloxane. In another
example, R.sub.12 is a alkylene oxide moiety represented by:
--CH.sub.2--O-- with the oxygen linked to a silicon on the backbone
of the trisiloxane.
[0089] Formula V-C: 20
[0090] wherein R.sub.13 is nil or a spacer; R.sub.14 is hydrogen;
alkyl or aryl; R.sub.15 is alkyl or aryl; and q is 1 to 12. The
spacer can be an organic spacer and can include one or more
--CH.sub.2-- groups. Other suitable spacers can include an
alkylene, alkylene oxide or a bivalent ether group. These spacers
can be substituted or unsubstituted. The above spacers can be
completely or partially halogenated. For instance, the above
spacers can be completely or partially fluorinated. In one example,
R.sub.13 is represented by: --(CH.sub.2).sub.3--.
[0091] Formula V-D: 21
[0092] wherein R.sub.16 is an organic spacer and p is 1 to 2. The
spacer can be an organic spacer and can include one or more
--CH.sub.2-- groups. Other suitable spacers can include an
alkylene, alkylene oxide or a bivalent ether group. These spacers
can be substituted or unsubstituted. The above spacers can be
completely or partially halogenated. For instance, the above
spacers can be completely or partially fluorinated. In one example,
R.sub.16 is a bivalent ether moiety represented by:
--CH.sub.2--O--(CH.sub.2).sub.3-- with the --(CH.sub.2).sub.3--
linked to a silicon on the backbone of the trisiloxane. In another
example, R.sub.16 is a alkylene oxide moiety represented by:
--CH.sub.2--O-- with the oxygen linked to a silicon on the backbone
of the trisiloxane.
[0093] One or more of the alkyl and aryl groups specified in
Formula V through Formula V-D can be substituted, unsubstituted,
halogenated, and/or fluorinated. In one example of a trisiloxane
according to Formula V, R.sub.7 is represented by Formula V-A with
R.sub.9 as an organic spacer and R.sub.8 is represented by Formula
V-C with R.sub.13 as an organic spacer. In another example of a
trisiloxane according to Formula V, R.sub.7 is represented by
Formula V-A with R.sub.9 as nil and R.sub.8 is represented by
Formula V-C with R.sub.13 as nil. In another example of a
trisiloxane according to Formula V, R.sub.7 is represented by
Formula V-B and R.sub.8 is represented by Formula V-D. In another
example of a trisiloxane according to Formula V, R.sub.7 is
represented by Formula V-A with R.sub.9 as an organic spacer and
R.sub.8 is represented by Formula V-D. In another example of a
trisiloxane according to Formula V, R.sub.7 is represented by
Formula V-A with R.sub.9 as an organic spacer and R.sub.8 is
represented by Formula V-D. In some instances, R.sub.1, R.sub.2,
R.sub.3, R.sub.4, R.sub.5, and R.sub.6 is each a methyl group.
[0094] Formula V-E through Formula V-H are examples of trisiloxanes
according to Formula V. Formula V-E and Formula V-F each illustrate
a trisiloxane where each of the terminal silicons are linked to a
side chain that includes a poly(ethylene oxide) moiety. Formula V-E
illustrates an organic spacer positioned between each poly(ethylene
oxide) moiety and the terminal silicon. Formula V-F illustrates
each of the terminal silicons linked directly to a poly(ethylene
oxide) moiety.
[0095] Formula V-E: 22
[0096] wherein n is 1 to 12and m is 1 to 12.
[0097] Formula V-F: 23
[0098] wherein n is 1 to 12 and m is 1 to 12.
[0099] Formula V-G and Formula V-H each illustrate a trisiloxane
with a terminal silicon linked to a side chain that includes a
cyclic carbonate moiety. Formula V-G illustrates one of the
terminal silicon linked to a side chain that includes a cyclic
carbonate moiety and one of the terminal silicons linked to a side
chain that includes a poly(ethylene oxide) moiety. Formula V-H
illustrates each of the terminal silicons linked to a side chain
that includes a cyclic carbonate moiety.
[0100] Formula V-G: 24
[0101] wherein m is 1 to 12.
[0102] Formula V-H: 25
[0103] Another suitable trisiloxane includes a backbone with a
first terminal silicon, a central silicon and a second terminal
silicon. The central silicon is linked to a central substituent.
The central substituent can be a side chain that includes a cyclic
carbonate moiety, or that includes a poly(alkylene oxide) moiety
linked directly to the central silicon. Alternately, the central
substituent can be a cross-link that cross links the trisiloxane to
a second siloxane and that includes a poly(alkylene oxide)
moiety.
[0104] In some instances, the trisiloxane includes not more than
two poly(alkylene oxide) moieties or not more than one
poly(alkylene oxide) moiety. Additionally or alternately, the
trisiloxane can include not more than two carbonate moieties or not
more than one carbonate moiety. The entities linked to the first
terminal silicon and the entities linked to the second terminal
silicon can each exclude a poly(alkylene oxide) moiety and/or each
exclude a cyclic carbonate moiety. Additionally or alternately, the
entities linked to the central silicon, other than the central
substituent, can exclude a poly(alkylene oxide) moiety and/or
exclude a cyclic carbonate moiety. In one example, each of the
entities linked to the silicons in the backbone of the trisiloxane,
other than the central substituent, exclude both a poly(alkylene
oxide) moiety and a cyclic carbonate moiety. Examples of entities
that may be linked to the silicons include, but are not limited to,
substituents such as side chains, halogens and cross-links.
[0105] An example of the trisiloxane is represented by the
following Formula VI: 26
[0106] wherein R.sub.19 is an alkyl group or an aryl group;
R.sub.20 is represented by Formula VI-A, Formula VI-B or Formula
VI-C; and the Zs are each an alkyl or an aryl group and can be the
same or different.
[0107] Formula VI-A: 27
[0108] wherein R.sub.21 is an organic spacer and p is 1 to 2.
Suitable organic spacers can include one or more --CH.sub.2--
groups. Other suitable spacers can include an alkylene, alkylene
oxide or a bivalent ether group. These spacers can be substituted
or unsubstituted. The above spacers can be completely or partially
halogenated. For instance, the above spacers can be completely or
partially fluorinated. In one example, R.sub.21 is a bivalent ether
moiety represented by: --CH.sub.2--O--(CH.sub.2).sub.3-- with the
--(CH.sub.2).sub.3-- linked to a silicon on the backbone of the
trisiloxane. In another example, R.sub.21 is a alkylene oxide
moiety represented by: --CH.sub.2--O-- with the oxygen linked to a
silicon on the backbone of the trisiloxane.
[0109] Formula VI-B: 28
[0110] wherein R.sub.23 is hydrogen; alkyl or aryl; R.sub.24 is
alkyl or aryl; and r is 1 to 12. The spacer can be an organic
spacer and can include one or more --CH.sub.2-- groups. Other
suitable spacers can include an alkylene, alkylene oxide or a
bivalent ether group. These spacers can be substituted or
unsubstituted. The above spacers can be completely or partially
halogenated. For instance, the above spacers can be completely or
partially fluorinated. In one example, R.sub.22 is represented by:
--(CH.sub.2).sub.3--.
[0111] Formula VI-C: 29
[0112] where R.sub.25 is nil or a spacer; R.sub.26 is nil or a
spacer; R.sub.27 is hydrogen, alkyl or aryl; second siloxane
represents another siloxane and n is 1 to 12. When R.sub.25 and/or
R.sub.26 is a spacer, the spacer can be an organic spacer and can
include one or more --CH.sub.2-- groups. Other suitable spacers can
include an alkylene, alkylene oxide or a bivalent ether group.
These spacers can be substituted or unsubstituted. The above
spacers can be completely or partially halogenated. For instance,
the above spacers can be completely or partially fluorinated. When
R.sub.26 is a spacer, R.sub.26 can be linked to a silicon in the
backbone of the second siloxane. When R.sub.26 is nil, the
poly(ethylene oxide) moiety can be linked to a silicon in the
backbone of the second siloxane. The second siloxane can represent
another trisiloxane. When the second siloxane is a trisiloxane,
R.sub.26 or the poly(ethylene oxide) moiety can be linked to a
central silicon in the backbone of the second trisiloxane.
[0113] One or more of the alkyl and aryl groups specified in
Formula VI through Formula VI-C can be substituted, unsubstituted,
halogenated, and/or fluorinated. In one example of a trisiloxane
according to Formula VI, R.sub.20 is represented by Formula VI-A.
In another example of the trisiloxane, R.sub.20 is represented by
Formula VI-B. In another example, R.sub.20 is represented by
Formula VI-C, R.sub.25 is nil, R.sub.26 is nil and the
poly(ethylene oxide) moiety is linked to a silicon in the backbone
of the second siloxane. In another example, R.sub.20 is represented
by Formula VI-C, R.sub.25 is a spacer, R.sub.26 is a spacer linked
to a silicon in the backbone of the second siloxane. In another
example, R.sub.25 is a spacer with the same structure as R.sub.26.
In another example of a trisiloxane according to Formula VI,
R.sub.19 and each of the Z represent methyl groups.
[0114] Formula VI-D through Formula VI-F are examples of
trisiloxanes according to Formula VI. Formula VI-D illustrates a
trisiloxane where the central silicon is linked to a side chain
that includes a poly(ethylene oxide) moiety linked directly to the
central silicon.
[0115] Formula VI-D: 30
[0116] wherein n is 1 to 12.
[0117] Formula VI-E and Formula VI-F illustrate trisiloxanes having
a central silicon linked to a cross link that includes a
poly(ethylene oxide) moiety and that cross-links the trisiloxane to
a second trisiloxane. Formula VI-E illustrates the cross link
including a spacer positioned between the poly(ethylene oxide)
moiety and each of the trisiloxanes. Formula VI-F illustrates a
silicon in the backbone of each trisiloxane linked directly to a
poly(ethylene oxide) moiety. Formula VI-E: 31
[0118] wherein n is 1 to 12.Formula VI-F: 32
[0119] wherein n is 1 to 12.
[0120] The solvent can include or consist of one or more
disiloxanes. Disloxanes can have a reduced viscosity relative to
similarly structured, polysiloxanes, tetrasiloxanes and
trisiloxanes. An example of a suitable disiloxane includes a
backbone with a first silicon and a second silicon. The first
silicon is linked to one or more first substituents that each
include a poly(alkylene oxide) moiety or a cyclic carbonate moiety.
The first substituent can be selected from a group consisting of a
first side-chain that includes a poly(alkylene oxide) moiety, a
first side-chain that includes a cyclic carbonate moiety or a cross
link that includes a poly(alkylene oxide) moiety and that cross
links the disiloxane to a second siloxane wherein side chains are
exclusive of cross links. As the number of substituents that
include a poly(alkylene oxide) moiety and/or a cyclic carbonate
moiety increase, the viscosity of an electrolyte can increase
undesirably and/or the ionic conductivity of an electrolyte can
decrease undesirably. As a result, embodiments of the disiloxane
include no more than one poly(alkylene oxide) moiety and/or no more
than one cyclic carbonate moiety. For instance, the entities linked
to the first silicon and the second silicon, other than the first
substituent, can each exclude a poly(alkylene oxide) moiety and/or
a cyclic carbonate moiety. In some instances, the disiloxane
excludes a poly(alkylene oxide) moieties or excludes cyclic
carbonate moieties.
[0121] The second silicon can be linked to a second substituent
selected from a group consisting of a second side-chain that
includes a poly(alkylene oxide) moiety, a second side-chain that
includes a cyclic carbonate moiety, an aryl group or an alkyl
group. In some instances, the second substituent is selected from a
group consisting of a second side-chain that includes a
poly(alkylene oxide) moiety and a second side-chain that includes a
cyclic carbonate moiety. As noted above, the viscosity of an
electrolyte can increase undesirably and/or the ionic conductivity
of an electrolyte can decrease undesirably as the number of
substituents that include a poly(alkylene oxide) moiety and/or a
cyclic carbonate moiety increases. As a result, the disiloxanes can
include no more than two poly(alkylene oxide) moiety and/or no more
than two cyclic carbonate moiety. For instance, the entities linked
to the first silicon and the second silicon, in addition to the
first substituent and the second substituent, can each exclude a
poly(alkylene oxide) moiety and/or a cyclic carbonate moiety.
[0122] Examples of suitable disiloxanes are disclosed in U.S.
Provisional Patent Application Ser. No. 60/543,951, filed on Feb.
11, 2004, entitled "Siloxane," and incorporated herein in its
entirety; and U.S. Provisional Patent Application Ser. No.
60/542,017, filed on Feb. 4, 2004, entitled "Nonaqueous Electrolyte
Solvents for Electrochemical Devices," and incorporated herein in
its entirety; and U.S. Provisional Patent Application Ser. No.
60/543,898, filed on Feb. 11, 2004, entitled "Siloxane Based
Electrolytes for Use in Electrochemical Devices," and incorporated
herein in its entirety.
[0123] Formula VII provides an example of a suitable disiloxane.
Formula VII: 33
[0124] wherein R.sub.1 is an alkyl group or an aryl group; R.sub.2
is an alkyl group or an aryl group; R.sub.3 is an alkyl group or an
aryl group; R.sub.4 is an alkyl group or an aryl group; R.sub.5 is
represented by Formula VII-A, Formula VII-B or Formula VII-C;
R.sub.6 is an alkyl group, an aryl group, represented by Formula
VII-D, or represented by Formula VII-E.
[0125] Formula VII-A: 34
[0126] wherein R.sub.9 is nil or a spacer; R.sub.10 is hydrogen;
alkyl or aryl; R.sub.11 is alkyl or aryl; and n is 1 to 12. The
spacer can be an organic spacer and can include one or more
--CH.sub.2-- groups. Other suitable spacers can include an
alkylene, alkylene oxide or a bivalent ether group. These spacers
can be substituted or unsubstituted. The above spacers can be
completely or partially halogenated. For instance, the above
spacers can be completely or partially fluorinated. In one example,
R.sub.9 is represented by: --(CH.sub.2).sub.3--.
[0127] Formula VII-B: 35
[0128] wherein R.sub.12 is an organic spacer and p is 1 to 2. The
spacer can be an organic spacer and can include one or more
--CH.sub.2-- groups. Other suitable spacers can include an
alkylene, alkylene oxide or a bivalent ether group. These spacers
can be substituted or unsubstituted. The above spacers can be
completely or partially halogenated. For instance, the above
spacers can be completely or partially fluorinated. In one example,
R.sub.12 is a bivalent ether moiety represented by:
--CH.sub.2--O--(CH.sub.2).sub.3-- with the --(CH.sub.2).sub.3--
linked to a silicon on the backbone of the disiloxane. In another
example, R.sub.12 is a alkylene oxide moiety represented by:
--CH.sub.2--O-- with the oxygen linked to a silicon on the backbone
of the disiloxane.
[0129] Formula VII-C: 36
[0130] where R.sub.14 is nil or a spacer; R.sub.15 is nil or a
spacer; R.sub.16 is hydrogen, alkyl or aryl; second siloxane
represents another siloxane and n is 1 to 12. The spacers can be
organic spacers and can include one or more --CH.sub.2-- groups.
Other suitable spacers can include an alkylene, alkylene oxide or a
bivalent ether group. These spacers can be the same or different
and can be substituted or unsubstituted. The above spacers can be
completely or partially halogenated. For instance, the above
spacers can be completely or partially fluorinated. In one example,
R.sub.14 and R.sub.15 are each represented by:
--(CH.sub.2).sub.3--.
[0131] Formula VII-D: 37
[0132] wherein R.sub.17 is nil or a spacer; R.sub.18 is hydrogen;
alkyl or aryl; R.sub.19 is alkyl or aryl; and q is 1 to 12. The
spacer can be an organic spacer and can include one or more
--CH.sub.2-- groups. Other suitable spacers can include an
alkylene, alkylene oxide or a bivalent ether group. These spacers
can be substituted or unsubstituted. The above spacers can be
completely or partially halogenated. For instance, the above
spacers can be completely or partially fluorinated. In one example,
R.sub.17 is represented by: --CH.sub.2--O--(CH.sub.2).sub.3-- with
the --(CH.sub.2).sub.3-- linked to a silicon on the backbone of the
disiloxane.
[0133] Formula VII-E: 38
[0134] wherein R.sub.20 is an organic spacer and p is 1 to 2. The
spacer can be an organic spacer and can include one or more
--CH.sub.2-- groups. Other suitable spacers can include an
alkylene, alkylene oxide or a bivalent ether group. These spacers
can be substituted or unsubstituted. The above spacers can be
completely or partially halogenated. For instance, the above
spacers can be completely or partially fluorinated. In one example,
R.sub.20 is a bivalent ether moiety represented by:
--CH.sub.2--O--(CH.sub.2).sub.3-- with the --(CH.sub.2).sub.3--
linked to a silicon on the backbone of the disiloxane. In another
example, R.sub.20 is a alkylene oxide moiety represented by:
--CH.sub.2--O-- with the oxygen linked to a silicon on the backbone
of the disiloxane.
[0135] In the disiloxanes illustrated in Formula VII: R.sub.5 can
represent Formula VII-A or Formula VII-B; or R.sub.5 can represent
Formula VII-A or Formula VII-C; or R.sub.5 can represent Formula
VII-B or Formula VII-C. Additionally or alternately: R.sub.6 can
represent an alkyl group or an aryl group or Formula VII-D; R.sub.6
can represent an alkyl group or an aryl group or Formula VII- E. In
some instances, R.sub.1, R.sub.2, R.sub.3 and R.sub.4 are each an
alkyl group. For instance, R.sub.1, R.sub.2, R.sub.3 and R.sub.4
can each be a methyl group.
[0136] In one example of the disiloxane, the first substituent is a
side chain that includes a poly(alkylene oxide) moiety. The
poly(alkylene oxide) moiety can include an oxygen linked directly
to the first silicon. For instance, the disiloxanes can be
represented by Formula VII with R.sub.5 represented by Formula
VII-A and R.sub.9 as nil. Alternately, a spacer can link the
poly(alkylene oxide) moiety to the first silicon. For instance, the
disiloxanes can be represented by Formula VII with R.sub.5
represented by Formula VII-A and R.sub.9 as a divalent organic
moiety.
[0137] When the first substituent is a side chain that includes a
poly(alkylene oxide) moiety, each of the entities linked to the
second silicon can be alkyl groups and/or aryl groups. For
instance, the second substituent can be an alkyl group or an aryl
group. The disiloxanes can be represented by Formula VII with
R.sub.5 represented by Formula VII-A and R.sub.6 as an alkyl group
or an aryl group. Formula VII-F provides an example of the
disiloxane. Formula VII-F: 39
[0138] where R.sub.21 is an alkyl group or an aryl group; R.sub.22
is an alkyl group or an aryl group; R.sub.23 is nil or a spacer;
R.sub.24 is a hydrogen atom or an alkyl group; R.sub.25 is an alkyl
group; Z is an alkyl or an aryl group and the Zs can be the same or
different and x is from 1 to 30. The spacer can be an organic
spacer and can include one or more --CH.sub.2-- groups. Other
suitable spacers can include an alkylene, alkylene oxide or a
bivalent ether group. These spacers can be substituted or
unsubstituted. The above spacers can be completely or partially
halogenated. For instance, the above spacers can be completely or
partially fluorinated. In one example, R.sub.23 has a structure
according to: --(CH.sub.2).sub.3--. In another example, the Zs,
R.sub.21, R.sub.22 and R.sub.25 are each a methyl group. In a
preferred example, the Zs, R.sub.21, R.sub.22 and R.sub.25 are each
a methyl group, R.sub.23 has a structure according to:
--(CH.sub.2).sub.3-- and R.sub.24 is a hydrogen. In a more
preferred example, the Zs, R.sub.21, R.sub.22 and R.sub.25 are each
a methyl group, R.sub.23 has a structure according to:
--(CH.sub.2).sub.3--; R.sub.24 is a hydrogen; and x is 3. A
preferred example of the disiloxane is provided in the following
Formula 40
[0139] wherein n is 1 to 12. A particularly preferred disiloxane is
represented by Formula VII-G with n=3.
[0140] When the first substituent is a side chain that includes a
poly(alkylene oxide) moiety, the second substituent can be a side
chain that includes a poly(alkylene oxide) moiety. For instance,
the disiloxane can be represented by Formula VII with R.sub.5
represented by Formula VII-A and R.sub.6 represented by Formula
VII-D. An example of the disiloxanes is provided in the following
Formula VII-H: 41
[0141] wherein R.sub.26 is an alkyl group or an aryl group;
R.sub.27 is an alkyl group or an aryl group; R.sub.28 is nil or a
spacer; R.sub.29 is a hydrogen atom or an alkyl group; R.sub.30 is
an alkyl group; R.sub.31 is an alkyl group or an aryl group;
R.sub.32 is an alkyl group or an aryl group; R.sub.33 is nil or a
spacer; R.sub.34 is a hydrogen atom or an alkyl group; R.sub.35 is
an alkyl group; x is from 1 to 30 and y is from 1 to 30. R.sub.28
and R.sub.33 can be the same or different. Each spacer can be an
organic spacer and can include one or more --CH.sub.2-- groups.
Other suitable spacers can include an alkylene, alkylene oxide or
bivalent ether. These spacers can be substituted or unsubstituted.
The above spacers can be completely or partially halogenated. For
instance, the above spacers can be completely or partially
fluorinated. In one example, R.sub.28 and R.sub.33 each has a
structure according to: --(CH.sub.2).sub.3--. In another example,
R.sub.26, R.sub.27, R.sub.31, and R.sub.32 are each an alkyl group.
In another example, R.sub.26, R.sub.27, R.sub.30, R.sub.31,
R.sub.32, and R.sub.35 are each a methyl group. In another example,
R.sub.30 and R.sub.35 have the same structure, R.sub.29 and
R.sub.34 have the same structure, R.sub.28 and R.sub.33 have the
same structure and R.sub.26, R.sub.27, R.sub.31, and R.sub.32 have
the same structure. A preferred example of the disiloxane is
presented in Formula VII-J: 42
[0142] wherein n is 1 to 12 and m is 1 to 12. A particularly
preferred disiloxane is represented by Formula VII-J with n=3 and
m=3.
[0143] When the first substituent is a side chain that includes a
poly(alkylene oxide) moiety, the second substituent can be a side
chain that includes a cyclic carbonate moiety. For instance, the
disiloxane can be represented by Formula VII with R.sub.5
represented by Formula VII-A and R.sub.6 represented by Formula
VII-E.
[0144] In another example of the disiloxane, the first substituent
cross links the disiloxane to a second siloxane and includes a
poly(alkylene oxide) moiety. The poly(alkylene oxide) moiety can
include an oxygen linked directly to the first silicon. For
instance, the disiloxane can be represented by Formula VII with
R.sub.5 represented by Formula VII-C and R.sub.14 as nil. In some
instances, the poly(alkylene oxide) moiety also includes a second
oxygen liked directly to the backbone of the second siloxane. For
instance, the disiloxane can be represented by Formula VII with
R.sub.5 represented by Formula VII-C, R.sub.14 as nil, and R.sub.15
as nil. Alternately, a spacer can link the poly(alkylene oxide)
moiety to the first silicon. For instance, the disiloxanes can be
represented by Formula VII with R.sub.5 represented by Formula
VII-A and R.sub.14 as a divalent organic moiety. In some instances,
the poly(alkylene oxide) moiety also includes a second spacer
linking the poly(alkylene oxide) moiety to the backbone of the
second siloxane. For instance, the disiloxane can be represented by
Formula VII with R.sub.5 represented by Formula VII-C, R.sub.14 as
a divalent organic moiety, and R.sub.15 as a divalent organic
moiety.
[0145] When the first substituent cross links the disiloxane to a
second siloxane and includes a poly(alkylene oxide) moiety, each of
the entities linked to the second silicon can be an aryl group or
an alkyl group. For instance, the second substituent can be an
alkyl group or an aryl group. The disiloxanes can be represented by
Formula VII with R.sub.5 represented by Formula VII-C and R.sub.6
as an alkyl group or an aryl group. Formula VII-K provides an
example of the disiloxane where the poly(alkylene oxide) moiety
includes an oxygen linked directly to the first silicon. Formula
VII-K: 43
[0146] wherein n is 1 to 12. Formula VII-L provides an example of
the disiloxane where an organic spacer is positioned between the
poly(alkylene oxide) moiety and the first silicon. Formula VII-L:
44
[0147] wherein n is 1 to 12.
[0148] When the first substituent cross links the disiloxane to a
second siloxane and includes a poly(alkylene oxide) moiety, the
second substituent can be a side chain that includes a
poly(alkylene oxide) moiety. For instance, the disiloxanes can be
represented by Formula VII with R.sub.5 represented by Formula
VII-C and R.sub.6 represented by Formula VII-D.
[0149] When the first substituent cross links the disiloxane to a
second siloxane and includes a poly(alkylene oxide) moiety, the
second substituent can be a side chain that includes a cyclic
carbonate moiety. For instance, the disiloxanes can be represented
by Formula VII with R.sub.5 represented by Formula VII-C and
R.sub.6 represented by Formula VII-E.
[0150] In another example of the disiloxane, the first substituent
is a side chain that includes a cyclic carbonate moiety. For
instance, the disiloxane can be represented by Formula VII with
R.sub.5 represented by Formula VII-B.
[0151] When the first substituent is a side chain that includes a
cyclic carbonate moiety, each of the entities linked to the second
silicon can be an aryl group or an alkyl group. For instance, the
second substituent can be an alkyl group or an aryl group. The
disiloxane can be represented by Formula VII with R.sub.5
represented by Formula VII-B and with R.sub.6 as an alkyl group or
an aryl group. A preferred example of the disiloxane is presented
by the following Formula VII-M: 45
[0152] When the first substituent is a side chain that includes a
cyclic carbonate moiety, the second substituent can be a side chain
that includes a cyclic carbonate moiety. For instance, the
disiloxane can be represented by Formula VII with R.sub.5
represented by Formula VII-B and R.sub.6 represented by Formula
VII-E. The structure of the first substituent can be the same as
the structure of the second substituent or can be different from
the structure of the second substituent. A preferred example of the
disiloxane is presented by the following Formula VII-N: 46
[0153] The electrolyte can include a single disiloxane and none or
more other siloxanes. Alternately, the electrolyte can include two
or more disiloxanes and none or more other siloxanes. Examples of
other suitable siloxanes include, but are not limited to,
trisiloxanes, tetrasiloxanes, pentasiloxanes, oligosiloxanes or
polysiloxanes. Suitable trisiloxanes are disclosed in U.S. patent
application Ser. No. (Not yet assigned), filed concurrently
herewith, entitled "Electrochemical Device Having Electrolyte
Including Trisiloxane" and incorporated herein in its entirety.
Suitable tetrasiloxanes are disclosed in U.S. patent application
Ser. No. (Not yet assigned), filed concurrently herewith, entitled
"Electrochemical Device Having Electrolyte Including Tetrasiloxane"
and incorporated herein in its entirety. In some instances, at
least one of the two or more disiloxanes is chosen from those
represented by Formula VII through Formula VII-N. Alternately, each
of the disiloxanes can be chosen from those represented by Formula
VII through Formula VII-N.
[0154] The solvent can include or consist of one or more silanes.
An example of the silane includes a silicon linked to one or more
first substituents that each include a poly(alkylene oxide) moiety
or a cyclic carbonate moiety. When a first substituent includes a
poly(alkylene oxide) moiety, the poly(alkylene oxide) moiety can
include an oxygen linked directly to the silicon. Alternately, the
first substituent can include a spacer positioned between the
poly(alkylene oxide) moiety and the silicon. Suitable spacers
include, but are not limited to, organic spacers. In some
instances, the poly(alkylene oxide) moiety is a poly(ethylene
oxide) moiety. In some instances, the poly(alkylene oxide) moiety
is an oligo(alkylene oxide) moiety having from 1 to 15 alkylene
oxide units. Examples of suitable silanes are disclosed in U.S.
Provisional Patent Application Ser. No. 60/601452, filed on Aug.
13, 2004, entitled "Electrolyte Including Silane for Use in
Electrochemical Devices," and incorporated herein in its
entirety.
[0155] The silane can include only one of the first substituents
linked to a silicon or a plurality of the first substituents linked
to the silicon. When the silane includes a plurality of the first
substituents, the silane can include two of the first substituents,
three of the first substituents or four of the first substituents.
When the silane includes fewer than four first substituents, the
additional substituent(s) linked to the silicon are second
substituents that each exclude a poly(alkylene oxide) moiety and a
cyclic carbonate moiety. Suitable second substituents include, but
are not limited to, alkyl groups, aryl groups and halogens. When
the silane includes a plurality of first substituents, the first
substituents can each be the same or can be different. In one
example, the silane includes a plurality of the first substituents
and each of the first substituents is different. Alternately, the
silane includes a plurality of the first substituents and a portion
of the first substituents is different from another portion of the
first substituents.
[0156] Examples of the first substituents include: a side-chain
that includes a poly(alkylene oxide) moiety; a side-chain that
includes a cyclic carbonate moiety; and a cross link that includes
a poly(alkylene oxide) moiety and that cross-links the silane to a
second silane where a cross link is exclusive of a side chain.
Accordingly, the silane can include one or more side-chains that
each include a poly(alkylene oxide) moiety and/or one or more
side-chains that each include a cyclic carbonate moiety and/or one
or more cross links that each include a poly(alkylene oxide) moiety
and that each cross-link the silane to a second silane.
[0157] In one example, the silane includes a silicon linked to one
or more side-chains that each include a poly(alkylene oxide) moiety
and linked to one or more second substituents. In another example,
the silane includes a silicon linked to one or more side-chains
that each include a cyclic carbonate moiety and linked to one or
more second substituents. In another example, the silane includes a
silicon linked to one or more cross links that each include a
poly(alkylene oxide) moiety and linked to one or more second
substituents.
[0158] In an example, the silane includes a silicon linked to one
or more side-chains that each include a poly(alkylene oxide)
moiety; to one or more side-chains that each include a cyclic
carbonate moiety; and to one or more second substituents. In
another example, the silane includes a silicon linked to one or
more side-chains that each include a cyclic carbonate moiety; to
one or more cross links that each include a poly(alkylene oxide)
moiety; and to one or more second substituents. In another example,
the silane includes a silicon linked to one or more side-chains
that each include a poly(alkylene oxide) moiety; to one or more
cross links that each include a poly(alkylene oxide) moiety; and to
one or more second substituents.
[0159] In one example, the silane includes a silicon linked to four
side-chains that each include a poly(alkylene oxide) moiety.
Accordingly, the silane can exclude cyclic carbonate moieties. In
another example, the silane includes a silicon linked to four
side-chains that each include a cyclic carbonate moiety.
Accordingly, the silane can exclude poly(alkylene oxide) moieties.
In another example, the silane includes a silicon linked to four
cross links that each include a poly(alkylene oxide) moiety.
[0160] An example of the silane includes a silicon linked to one or
more first substituents that each include a poly(alkylene oxide)
moiety or a cyclic carbonate moiety. When a first substituent
includes a poly(alkylene oxide) moiety, the poly(alkylene oxide)
moiety can include an oxygen linked directly to the silicon.
Alternately, the first substituent can include a spacer positioned
between the poly(alkylene oxide) moiety and the silicon. Suitable
spacers include, but are not limited to, organic spacers. In some
instances, the poly(alkylene oxide) moiety is a poly(ethylene
oxide) moiety. In some instances, the poly(alkylene oxide) moiety
is an oligo(alkylene oxide) moiety having from 1 to 15 alkylene
oxide units.
[0161] The silane can include only one of the first substituents
linked to a silicon or a plurality of the first substituents linked
to the silicon. When the silane includes a plurality of the first
substituents, the silane can include two of the first substituents,
three of the first substituents or four of the first substituents.
When the silane includes fewer than four first substituents, the
additional substituent(s) linked to the silicon are second
substituents that each exclude a poly(alkylene oxide) moiety and a
cyclic carbonate moiety. Suitable second substituents include, but
are not limited to, alkyl groups, aryl groups and halogens. When
the silane includes a plurality of first substituents, the first
substituents can each be the same or can be different. In one
example, the silane includes a plurality of the first substituents
and each of the first substituents is different. Alternately, the
silane includes a plurality of the first substituents and a portion
of the first substituents is different from another portion of the
first substituents.
[0162] Examples of the first substituents include: a side-chain
that includes a poly(alkylene oxide) moiety; a side-chain that
includes a cyclic carbonate moiety; and a cross link that includes
a poly(alkylene oxide) moiety and that cross-links the silane to a
second silane where a cross link is exclusive of a side chain.
Accordingly, the silane can include one or more side-chains that
each include a poly(alkylene oxide) moiety and/or one or more
side-chains that each include a cyclic carbonate moiety and/or one
or more cross links that each include a poly(alkylene oxide) moiety
and that each cross-link the silane to a second silane.
[0163] In one example, the silane includes a silicon linked to one
or more side-chains that each include a poly(alkylene oxide) moiety
and linked to one or more second substituents. In another example,
the silane includes a silicon linked to one or more side-chains
that each include a cyclic carbonate moiety and linked to one or
more second substituents. In another example, the silane includes a
silicon linked to one or more cross links that each include a
poly(alkylene oxide) moiety and linked to one or more second
substituents.
[0164] In an example, the silane includes a silicon linked to one
or more side-chains that each include a poly(alkylene oxide)
moiety; to one or more side-chains that each include a cyclic
carbonate moiety; and to one or more second substituents. In
another example, the silane includes a silicon linked to one or
more side-chains that each include a cyclic carbonate moiety; to
one or more cross links that each include a poly(alkylene oxide)
moiety; and to one or more second substituents. In another example,
the silane includes a silicon linked to one or more side-chains
that each include a poly(alkylene oxide) moiety; to one or more
cross links that each include a poly(alkylene oxide) moiety; and to
one or more second substituents.
[0165] In one example, the silane includes a silicon linked to four
side-chains that each include a poly(alkylene oxide) moiety.
Accordingly, the silane can exclude cyclic carbonate moieties. In
another example, the silane includes a silicon linked to four
side-chains that each include a cyclic carbonate moiety.
Accordingly, the silane can exclude poly(alkylene oxide) moieties.
In another example, the silane includes a silicon linked to four
cross links that each include a poly(alkylene oxide) moiety.
[0166] A suitable silane can be represented by the following
Formula VIII: SiR.sub.4-x-yR'.sub.xR".sub.y; wherein R is a second
substituent and an alkyl group, an aryl group or a halogen,
R'.sub.x is a first substituent that includes a poly(alkylene
oxide) moiety and can be represented by Formula VIII-A or Formula
VIII-C, R".sub.y is a first substituent that includes a cyclic
carbonate moiety and can be represented by Formula VIII-B, x
indicates the number of R' substituents included in the silane and
is 0 to 4, y indicates the number of R" substituents included in
the silane is 0 to 4, 4-x-y indicates the number of R substituents,
and x+y is at least 1.
[0167] Formula VIII-A: 47
[0168] wherein R.sub.9 is nil or an organic spacer; R.sub.10 is
hydrogen; alkyl or aryl; R.sub.11 is alkyl or aryl; and n is 1 to
15. The spacer can be an organic spacer and can include one or more
--CH.sub.2-- groups. Other suitable spacers can include an
alkylene, alkylene oxide or a bivalent ether group. These spacers
can be substituted or unsubstituted. In one example, R.sub.9 is
represented by: --(CH.sub.2).sub.3--.
[0169] Formula VIII-B: 48
[0170] wherein R.sub.12 is an organic spacer and p is 1 to 2. The
spacer can be an organic spacer and can include one or more
--CH.sub.2-- groups. Other suitable spacers can include an
alkylene, alkylene oxide or a bivalent ether group. These spacers
can be substituted or unsubstituted. The above spacers can be
completely or partially halogenated. For instance, the above
spacers can be completely or partially fluorinated. In one example,
R.sub.12 is a bivalent ether moiety represented by:
--CH.sub.2--O--(CH.sub.2).sub.3-- with the --(CH.sub.2).sub.3--
linked to a silicon on the backbone of the silane. In another
example, R.sub.12 is an alkylene oxide moiety represented by:
--CH.sub.2--O-- with the oxygen linked to a silicon on the backbone
of the silane.
[0171] Formula VIII-C: 49
[0172] where R.sub.14 is nil or a spacer; R.sub.15 is nil or a
spacer; R.sub.16 is hydrogen, alkyl or aryl; second silane
represents another silane and n is 1 to 15. The spacers can be
organic spacers and can include one or more --CH.sub.2-- groups.
Other suitable spacers can include an alkylene, alkylene oxide or a
bivalent ether group. These spacers can be the same or different
and can be substituted or unsubstituted. In one example, R.sub.14
and R.sub.15 are each represented by: --(CH.sub.2).sub.3--. The
second silane can be represented by:
--SiR.sub.3-p-qR'.sub.pR".sub.q, wherein R are each an alkyl group
or an aryl group, R' is a substituent that includes a poly(alkylene
oxide) moiety and can be represented by Formula VIII-A or Formula
VIII-C, R" is a substituent that includes a cyclic carbonate moiety
and can be represented by Formula VIII-B, p is the number of R'
substituents included on the second silane and is 0 to 3, q is the
number of R" substituents included on the second silane, 3-p-q is
the number of R substituents, and is 0 to 3. In one example, p is 0
and q is 0. In another example, p+q is greater than or equal to 1.
In yet another example, p is greater than or equal to 1. In still
another example, q is greater than or equal to 1. In another
example, R' is represented by Formula VIII-A and R" is represented
by Formula VIII-B, p is 0 to 3 and q is 0 to 3.
[0173] One or more of the alkyl and aryl groups specified in
Formula VIII through Formula VIII-C can be substituted,
unsubstituted, halogenated, and/or fluorinated. When the silane
includes more than one substituent represented by Formula VIII-A,
the entities can be the same or different. When the silane includes
more than one substituent represented by Formula VIII-B, the
entities can be the same or different. When the silane includes
more than one substituent represented by Formula VIII-C, the
entities can be the same or different.
[0174] In one example of the silane according to Formula VIII, x=0.
In another example, x is 1 to 3. In another example, y=0. In still
another example, y is 1 to 3. In another example, x+y=4 or
x+y=2.
[0175] In some instances, R' is represented by Formula VIII-A, x is
greater than 0, and R.sub.9 is nil. In other instances, R' is
represented by Formula VIII-A and R.sub.9 is an organic spacer. In
an example, R" is represented by Formula VIII-B and y is greater
than 0. In another example, R' is represented by Formula VIII-C, x
is greater than 0, R.sub.14 is nil and R.sub.15 is nil. In still
another example, R' is represented by Formula VIII-C, x is greater
than 0, R.sub.14 is an organic spacer and R.sub.15is an organic
spacer.
[0176] When the silane includes more than one substituent
represented by Formula VIII-A, the entities can be the same or
different. When the silane includes more than one substituent
represented by Formula VIII-B, the entities can be the same or
different. When the silane includes more than one substituent
represented by formula VIII-C, the entities can be the same or
different.
[0177] A preferred silane includes a silicon linked to one side
chain that includes a poly(alkylene oxide) moiety and linked to
three second substituents. For instance, the silane can be
represented by Formula VIII with x=1, y=0 and the R' represented by
Formula VIII-A. Formula VIII-D presents an example of the silane
that includes a silicon linked to one side chain that includes a
poly(ethylene oxide) moiety, and linked to three alkyl groups. The
poly(ethylene oxide) moiety of Formula VIII-D includes an oxygen
liked directly to the silicon. Formula VIII-D: 50
[0178] wherein n is 1 to 15. In a preferred silane according to
Formula VIII-D, n=3. Formula VIII-E presents an example of the
silane that includes a silicon linked to one side chain that
includes a poly(alkylene oxide) moiety, and linked to three alkyl
groups. The side chain of Formula VIII-E includes an organic spacer
positioned between the silicon and the poly(ethylene oxide) moiety.
Formula VIII-E: 51
[0179] wherein n is 1 to 15. In a preferred silane according to
Formula VIII-E, n=3. Formula VIII-F presents another example of the
silane that includes a silicon linked to one side chain that
includes a poly(alkylene oxide) moiety, and linked to three alkyl
groups. The side chain of Formula VIII-F includes an organic spacer
positioned between the silicon and the poly(alkylene oxide) moiety.
Formula VIII-F: 52
[0180] wherein n is 1 to 15. In a preferred silane according to
Formula VIII-F, n=3.
[0181] A preferred silane includes a silicon linked to two side
chains that each include a poly(alkylene oxide) moiety and linked
to two second substitutents. For instance, the silane can be
represented by Formula VIII with x=2 and y=0. One or both R' can be
represented by Formula VIII-A. One or both R' can be represented by
Formula VIII-C. In some instances, one R' is represented by Formula
VIII-A and one R' is represented by Formula VIII-C. Formula VIII-G
is an example of the silane that includes a silicon linked to two
side chains that each include a poly(ethylene oxide) moiety and
linked to two alkyl groups. Formula VIII-G: 53
[0182] wherein m is 1 to 15, n is 1 to 15 and m can be different
from n or the same as n. In a preferred silane according to Formula
VIII-G, m=3 and n=3. Formula VIII-H is an example of the silane
that includes a silicon linked to two side chains that each include
a poly(ethylene oxide) moiety, and linked to an alkyl group, and
linked to an aryl group.
[0183] Formula VIII-H: 54
[0184] wherein m is 1 to 15, n is 1 to 15 and m can be different
from n or the same as n. In a preferred silane according to Formula
VIII-H, m=3 and n=3.
[0185] Another preferred silane includes a silicon linked to one
side chain that includes a cyclic carbonate moiety and linked to
three second substituents. For instance, the silane can be
represented by Formula VIII with x=0 and y=1. Formula VIII-J is a
preferred example of the silane that includes a silicon linked to a
side chain that includes a cyclic carbonate moiety and linked to
three alkyl groups. Formula VIII-J: 55
[0186] Another preferred silane includes a silicon linked to a
cross link that includes a poly(alkylene oxide) moiety and linked
to three second substituents. For instance, the silane can be
represented by Formula VIII with x=1, y=0 and the R' represented by
Formula VIII-C. Formula VIII-K is a preferred example of the silane
that includes a silicon linked to a cross link that includes a
poly(alkylene oxide) moiety and linked to three alkyl groups. The
poly(alkylene oxide) moiety of Formula VIII-K includes an oxygen
liked directly to the silicon of each silane. Formula VIII-K:
56
[0187] wherein n is 1 to 15. In a preferred silane according to
Formula VIII-K, n=4.
[0188] The electrolyte can include a single silane. Alternately,
the electrolyte can include a plurality of silanes. When the
electrolyte includes a plurality of silanes, at least one of the
silanes can be chosen from those represented by Formula VIII
through Formula VIII-K. Alternately, each of the silanes can be
chosen from those represented by Formula VIII through Formula
VIII-K. In some instances, the electrolyte includes a silane that
excludes poly(alkylene oxide) moieties and a silane that excludes
cyclic carbonate moieties. For instance, the electrolyte can
include a silane that includes one or more poly(alkylene oxide)
moieties and a silane that excludes poly(alkylene oxide) moieties
moieties. Alternately, the electrolyte can include a silane that
includes one or more cyclic carbonate moieties and a silane that
excludes cyclic carbonate moieties. In a preferred example, the
electrolyte includes a blend of a silane according to Formula
VIII-J and a silane according to Formula VIII-F. In another
preferred example, the electrolyte includes a blend of a silane
according to Formula VIII-J and a silane according to Formula
VIII-D.
[0189] In some instances, the solvent includes more than one of the
siloxanes or more than one of the silanes. Further, the solvent can
include one or more siloxanes combined with one or more silanes.
The combination of a silane with other silanes and/or with other
siloxanes can reduce the viscosity of the blended solvent.
Additionally, the inventors believe that the silanes can improve
the mobility of poly(alkylene oxide) in other siloxanes or silanes.
Additionally, the combination of a silane with other silanes and/or
siloxanes can increase the ability of the solvent to dissociate the
salts employed in electrolyte and can accordingly increase the
concentration of free ions in the electrolyte. These features can
further enhance the ionic conductivity of the electrolytes.
[0190] The above siloxanes and silanes can be generated by
employing nucleophilic substitutions, hydrosilylation and/or
dehydrogenation reactions. Methods for generating the silanes and
siloxanes can be found in U.S. patent application Ser. No.
10/810,019, filed on Mar. 25, 2004, entitled "Polysiloxane for Use
in Electrochemical Cells;" U.S. Provisional Patent Application Ser.
No. 60/543,951, filed on Feb. 11, 2004, entitled "Siloxane;" U.S.
Provisional Patent Application Ser. No. 60/542,017, filed on Feb.
4, 2004, entitled "Nonaqueous Electrolyte Solvents for
Electrochemical Devices," and incorporated herein in its entirety;
and U.S. Provisional Patent Application Ser. No. 60/543,898, filed
on Feb. 11, 2004, entitled "Siloxane Based Electrolytes for Use in
Electrochemical Devices," and incorporated herein in its entirety;
and U.S. Provisional Patent Application Ser. No. 60/601,452, filed
on Aug. 13, 2004, entitled "Electrolyte Including Silane for Use in
Electrochemical Devices," and incorporated herein in its
entirety.
[0191] In some instances, the solvent includes one or more organic
solvents in addition to one or more of the silanes and/or in
addition to one or more of the siloxanes. Organic solvents can
reduce the viscosity of the siloxanes and/or the silanes.
Additionally or alternately, the addition of organic salts can
increase the ionic conductivity of the electrolyte. Examples of
suitable organic solvents include, but are not limited to, cyclic
carbonates such as propylene carbonate (PC), ethylene carbonate
(EC), butylene carbonate (BC) and vinylene carbonate (VC), linear
carbonates such as dimethyl carbonate (DMC), diethyl carbonate
(DEC), ethylmethyl carbonate (EMC) and dipropyl carbonate (DPC),
dialkyl carbonates such as diglyme, trigylme, tetragylme,
1,2-dimethoxyethane (DME), methyl propyl carbonate, ethyl propyl
carbonate, aliphatic carboxylate esters such as methyl formate,
methyl acetate and ethyl propionate, gamma.-lactones such as
.gamma.-butyrolactone, linear ethers such as 1,2-ethoxyethane (DEE)
and ethoxymethoxyethane (EME), cyclic ethers such as
tetrahydrofuran and 2-methyltetrahydrofuran, and aprotic organic
solvents such as dimethylsulfoxide, 1,3-dioxolane, formamide,
acetoamide, dimethylformamide, dioxolane, acetonitrile,
propylnitrile, nitromethane, ethylmonoglyme, triester phosphate,
timethoxymethane, dioxolane-derivatives, sulphorane,
methylsulphorane, 1,3-diemthyl-2-imidazoline,
3-methyl-2-oxazolidinone, propylene carbonate-derivatives,
tetrahydrofuran-derivatives, ethylether, 1,3-propanesultone,
anisole, N-methylpyrrolidone and fluorinated carboxylate esters. In
some instances, the solvent excludes organic solvents. When the
solvent includes one or more organic solvents a suitable volume
ratio of the total organic solvents to the total siloxane and
silane is greater than 1:99, 1:9, or 3:7 and/or less than 9:1, 4:1
or 7:3.
[0192] The electrolyte can optionally include one or more additives
that form a passivation layer on the anode. The additives can be
reduced and/or polymerize at the surface of the anode to form the
passivation layer. Vinyl ethylene carbonate (VEC) and vinyl
carbonate (VC) are examples of additives that can form a
passivation layer by being reduced and polymerizing to form a
passivation layer. When they see an electron at the surface of a
carbonaceous anode, they are reduced to Li.sub.2CO.sub.3 and
butadiene that polymerizes at the surface of the anode. Ethylene
sulfite (ES) and propylene sulfite (PS) form passivation layers by
mechanisms that are similar to VC and VEC. In some instances, one
or more of the additives has a reduction potential that exceeds the
reduction potential of the components of the solvent. For instance,
VEC and VC have a reduction potential of about 2.3V. This
arrangement of reduction potentials can encourage the additive to
form the passivation layer before reduction of other electrolyte
components and can accordingly reduce consumption of other
electrolyte components.
[0193] Suitable additives include, but are not limited to,
carbonates having one or more unsaturated substituents. For
instance, suitable additives include unsaturated and unsubstituted
cyclic carbonates such as vinyl carbonate (VC); cyclic alkylene
carbonates having one or more unsaturated substituents such as
vinyl ethylene carbonate (VEC), and o-phenylene carbonate (CC,
C.sub.7H.sub.4O.sub.3); cyclic alkylene carbonates having one or
more halogenated alkyl substituents such as ethylene carbonate
substituted with a trifluormethyl group (trifluoropropylene
carbonate, TFPC); linear carbonates having one or more unsaturated
substituents such as ethyl 2-propenyl ethyl carbonate
(C.sub.2H.sub.5CO.sub.3C.sub.3H.sub.5); saturated or unsaturated
halogenated cyclic alkylene carbonates such as fluoroethylene
carbonate (FEC) and chloroethylene carbonate (ClEC). Other suitable
additives include, acetates having one or more unsaturated
substituents such as vinyl acetate (VA). Other suitable additives
include cyclic alkyl sulfites and linear sulfites. For instance,
suitable additives include unsubstituted cyclic alkyl sulfites such
as ethylene sulfite (ES); substituted cyclic alkylene sulfites such
as ethylene sulfite substituted with an alkyl group such as a
methyl group (propylene sulfite, PS); linear sulfites having one or
more one more alkyl substituents and dialkyl sulfites such as
dimethyl sulfite (DMS) and diethyl sulfite (DES). Other suitable
additives include halogenated-gamma-butyrolactones such as
bromo-gamma-butyrolactone (BrGBL) and fluoro-gamma-butyrolactone
(FGBL).
[0194] The additives can include or consist of one or more
additives selected from the group consisting of: dimethyl sulfite
(DMS), diethyl sulfite (DES), bromo-gamma-butyrolactone (BrGBL),
fluoro-gamma-butyrolact- one (FGBL), vinyl carbonate (VC), vinyl
ethylene carbonate (VEC), ethylene sulfite (ES), CC,
trifluoropropylene carbonate (TFPC), 2-propenyl ethyl carbonate,
fluoroethylene carbonate (FEC), chloroethylene carbonate (ClEC),
vinyl acetate (VA), propylene sulfite (PS), 1,3 dimethyl butadiene,
styrene carbonate, phenyl ethylene carbonate (PhEC), aromatic
carbonates, vinyl pyrrole, vinyl piperazine, vinyl piperidine,
vinyl pyridine, and mixtures thereof. In another example, the
electrolyte includes or consists of one or more additives selected
from the group consisting of vinyl carbonate (VC), vinyl ethylene
carbonate (VEC), ethylene sulfite (ES), propylene sulfite (PS), and
phenyl ethylene carbonate (PhEC). In a preferred example, the
electrolyte includes or consists of one or more additives selected
from the group consisting of vinyl carbonate (VC), vinyl ethylene
carbonate (VEC), ethylene sulfite (ES), and propylene sulfite (PS).
In another preferred example, the electrolyte includes vinyl
carbonate (VC) and/or vinyl ethylene carbonate (VEC).
[0195] In some conditions, certain organoborate salts, such as
LiDfOB, can form a passivation layer. As a result, the desirability
and/or concentration of additives may be reduced when organoborate
are employed as salts. In some instances, the concentration of
additives in the electrolyte generally does not greatly exceed the
concentration needed to form the passivation layer. As a result,
the additives are generally present in smaller concentrations than
salts. A suitable concentration for an additive in the electrolyte
includes, but is not limited to, concentrations greater than 0.1 wt
%, greater than 0.5 wt % and/or less than 5 wt %, less than 20 wt
%, or less than 35 wt % where each of the wt % refers to the
percentage of the total weight of solvent plus additive. In a
preferred embodiment, the concentration of the additive is less
than 3 wt % or less than 2 wt %.
[0196] The electrolyte can be a liquid. In some instances, the
electrolyte is a solid or a gel. For instance, the electrolyte can
include a network polymer that interacts with the solvent to form
an interpenetrating network. The interpenetrating network can serve
as a mechanism for providing a solid electrolyte or gel
electrolyte. Alternately, the electrolyte can include one or more
solid polymers that are each a solid at room temperature when
standing alone. The solid polymer can be employed in conjunction
with the solvent to generate an electrolyte such as a plasticized
electrolyte as a solid or as a gel. Alternately, one or more
silanes and/or one or more siloxanes in the solvent can be cross
linked to provide a solid or gel electrolyte. A polysiloxane is an
example of a cross-linkable solvent. Suitable examples for method
of forming a cross linked polymer are disclosed in U.S. patent
application Ser. No. 10/810,019, filed on Mar. 25, 2004, entitled
"Polysiloxane for Use in Electrochemical Cells" and incorporated
herein in its entirety.
[0197] The battery can be a primary battery or a secondary battery.
Further, the above cathode, anode and electrolyte combinations can
be employed in other electrochemical devices such as capacitors and
hybrid capacitors/batteries.
EXAMPLE 1
[0198] A variety of 2032 type button cells were generated having a
structure according to FIG. 2. The button cells include a separator
2 positioned between a cathode 1 and an anode 3. The anode and
cathode are positioned in a chamber defined by a case 4, a gasket 5
and a cover 6. A spacer 7 and a spring washer 8 are positioned
between the anode 3 and the case 4. The spacer 7 and spring washer
8 were made of stainless steel. The separator was a 25 .mu.m thick
polyethylene porous membrane (Tonen Co., Ltd.). An electrolyte
positioned between the case 4 and the cover 6 activates the anode
and the cathode.
[0199] The cathodes were generated by mixing 42 g
LiNi.sub.0.8Co.sub.0.15A- l.sub.0.05O.sub.2 (Toda Kogyo Co., Ltd.,
CA1505N) with 33.3 g of 12 wt %-solution of PVdF in n-methyl
pyrolidone (NMP) (Kureha Co., Ltd., PVdF1120), 2 g acetylene black
and 2 g graphite (Timcal Co., Ltd., SFG6) in a mixer. The above
mixture was coated on 20 um thick of aluminum foil substrate with a
doctor blade. The result was dried in an oven preset at 80.degree.
C. and pressed down to a 105 .mu.m thickness using a roll press.
Cathodes 14 mm in diameter were punched out of the result.
[0200] The anodes were generated by mixing 46.56 g Mesocarbon
Microbeads (Osaka Gas Co., Ltd., MCMB 25-28) and 1.44 g vapor grown
carbon fiber (Showa denko Co., Ltd. VGCF,) with 41.03 g of a 13 wt
% solution of PVdF in NMP (Kureha Co., Ltd., PVdF9130) in a mixer.
The result was coated onto a 10 um thickness of copper foil with a
doctor blade. The result was dried in an oven preset at 80.degree.
C. The dried result was then pressed to a 65 .mu.m thickness.
Anodes (15 mm in diameter) were punched out of the result.
[0201] A disiloxane was generated with a structure according to
Formula VII-J with n=3 and m=3. A first electrolyte was generated
by dissolving LiBOB to 1.0 M in the disiloxane. A second
electrolyte was generated by dissolving LiDfOB to 1.0 M in the
disiloxane. A third electrolyte was generated by dissolving
LiPF.sub.6 to 1.0 M in a blend of 2 wt % VC and 98 wt % of the
disiloxane.
[0202] The button cells were generated with each of the
electrolytes. The button cells were repeatedly charged and
discharged between 2.7 V and 4.0 V. During formation of a
passivation layer in the first four cycles, the cells were charged
using constant current at a rate of C/20 followed by charging at
constant voltage until the current falls to C/100. During the same
four cycles, the cells were discharged at C/20. During the
subsequent cycles, the cells were charged using constant current at
a rate of C/5 followed by charging at constant voltage until the
current falls to C/100 and were discharged at C/5. The tests were
carried out at 37.degree. C.
[0203] FIG. 3 presents the cycling data for each of the batteries
as a plot of discharge capacity retention versus cycle number. The
electrolyte having the LiDfOB showed the best cycling performance.
For instance, the electrolyte having the LiDfOB has a discharge
capacity retention of about 90% at the 200 th cycle. Accordingly,
the battery can have a discharge capacity retention of more than
85% at the 200 th cycle when the battery is cycled between 2.7 V
and 4.0 V after formation of a passivation layer. Further, the
battery can have a discharge capacity retention of more than 88% at
the 200 th cycle when the battery is cycled between 2.7 V and 4.0 V
after formation of a passivation layer.
EXAMPLE 2
[0204] A silane was generated with a structure according to Formula
VIII-G with m=3 and n=3. A fourth electrolyte was generated by
dissolving LiBOB to 1.0 M in the silane. A fifth electrolyte was
generated by dissolving LiDfOB to 1.0 M in the silane.
[0205] Button cells were generated with the fourth electrolyte and
the fifth electrolyte as described in Example 1. The button cells
were repeatedly charged and discharged between 2.7 V and 4.0 V.
During formation of a passivation layer in the first four cycles,
the cells were charged using constant current at a rate of C/20
followed by charging at constant voltage until the current falls to
C/100. During the same four cycles, the cells were discharged at
C/20. During the subsequent cycles, the cells were charged using
constant current at a rate of C/5 followed by charging at constant
voltage until the current falls to C/100 and were discharged at
C/5. The tests were carried out at 37.degree. C.
[0206] FIG. 4 presents the cycling data for each of the batteries
as a plot of discharge capacity retention versus cycle number. The
electrolyte having the LiDfOB (the fifth electrolyte) showed the
best cycling performance. For instance, the fourth electrolyte has
a discharge capacity retention of about 95% at the 200 th cycle.
Accordingly, the battery can have a discharge capacity retention of
more than 85% at the 200 th cycle when the battery is cycled
between 2.7 V and 4.0 V after formation of a passivation layer.
Further, the battery can have a discharge capacity retention of
more than 90% at the 200 th cycle when the battery is cycled
between 2.7 V and 4.0 V after formation of a passivation layer.
Further, the performance of the fifth electrolyte is improved
relative to the performance of the second electrolyte from example
2. The improved performance result from the use of the silane
solvent in place of the disiloxanes solvent.
[0207] Other embodiments, combinations and modifications of this
invention will occur readily to those of ordinary skill in the art
in view of these teachings. Therefore, this invention is to be
limited only by the following claims, which include all such
embodiments and modifications when viewed in conjunction with the
above specification and accompanying drawings.
* * * * *